Assemblies
Assembly Name:
30S small ribosomal subunit and RNA and DNA
Multimeric state:
hetero 68-mer
PDBe Complex ID:
PDB-CPX-280374
Macromolecules
Chain: 0
Length: 103 amino acids
Theoretical weight: 11.59 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal prokaryotic L21 protein
Length: 103 amino acids
Theoretical weight: 11.59 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P0AG48 (Residues: 1-103; Coverage: 100%)
Pfam: Ribosomal prokaryotic L21 protein
Chain: 1
Length: 110 amino acids
Theoretical weight: 12.25 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L22p/L17e
Length: 110 amino acids
Theoretical weight: 12.25 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P61175 (Residues: 1-110; Coverage: 100%)
Pfam: Ribosomal protein L22p/L17e
Chain: 2
Length: 100 amino acids
Theoretical weight: 11.22 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L23
Length: 100 amino acids
Theoretical weight: 11.22 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P0ADZ0 (Residues: 1-100; Coverage: 100%)
Pfam: Ribosomal protein L23
Chain: 3
Length: 104 amino acids
Theoretical weight: 11.34 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam:
Length: 104 amino acids
Theoretical weight: 11.34 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P60624 (Residues: 1-104; Coverage: 100%)
Pfam:
Chain: 4
Length: 94 amino acids
Theoretical weight: 10.71 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal L25p family
Length: 94 amino acids
Theoretical weight: 10.71 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P68919 (Residues: 1-94; Coverage: 100%)
Pfam: Ribosomal L25p family
Chain: 9
Length: 165 amino acids
Theoretical weight: 17.74 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L10
Length: 165 amino acids
Theoretical weight: 17.74 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7J3 (Residues: 1-165; Coverage: 100%)
Pfam: Ribosomal protein L10
Chain: AB
Length: 162 amino acids
Theoretical weight: 18.36 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Transcription termination factor nusG
Length: 162 amino acids
Theoretical weight: 18.36 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P0AFW0 (Residues: 1-162; Coverage: 100%)
Pfam: Transcription termination factor nusG
Chain: AF
Length: 91 amino acids
Theoretical weight: 10.25 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: RNA polymerase Rpb6
Length: 91 amino acids
Theoretical weight: 10.25 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A800 (Residues: 1-91; Coverage: 100%)
Pfam: RNA polymerase Rpb6
Chain: AG
Length: 495 amino acids
Theoretical weight: 54.93 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam:
Length: 495 amino acids
Theoretical weight: 54.93 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P0AFF6 (Residues: 1-495; Coverage: 100%)
Pfam:
Chain: C
Length: 75 amino acids
Theoretical weight: 9.01 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S18
Length: 75 amino acids
Theoretical weight: 9.01 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7T7 (Residues: 1-75; Coverage: 100%)
Pfam: Ribosomal protein S18
Chain: E
Length: 87 amino acids
Theoretical weight: 9.71 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S20
Length: 87 amino acids
Theoretical weight: 9.71 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7U7 (Residues: 1-87; Coverage: 100%)
Pfam: Ribosomal protein S20
Chain: F
Length: 71 amino acids
Theoretical weight: 8.52 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S21
Length: 71 amino acids
Theoretical weight: 8.52 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P68679 (Residues: 1-71; Coverage: 100%)
Pfam: Ribosomal protein S21
Chain: G
Length: 241 amino acids
Theoretical weight: 26.78 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S2
Length: 241 amino acids
Theoretical weight: 26.78 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7V0 (Residues: 1-241; Coverage: 100%)
Pfam: Ribosomal protein S2
Chain: H
Length: 557 amino acids
Theoretical weight: 61.24 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: S1 RNA binding domain
Length: 557 amino acids
Theoretical weight: 61.24 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0AG67 (Residues: 1-557; Coverage: 100%)
Pfam: S1 RNA binding domain
Chain: I
Length: 233 amino acids
Theoretical weight: 26.03 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam:
Length: 233 amino acids
Theoretical weight: 26.03 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7V3 (Residues: 1-233; Coverage: 100%)
Pfam:
Chain: L
Length: 135 amino acids
Theoretical weight: 15.73 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S6
Length: 135 amino acids
Theoretical weight: 15.73 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P02358 (Residues: 1-135; Coverage: 100%)
Pfam: Ribosomal protein S6
Chain: M
Length: 179 amino acids
Theoretical weight: 20.06 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S7p/S5e
Length: 179 amino acids
Theoretical weight: 20.06 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P02359 (Residues: 1-179; Coverage: 100%)
Pfam: Ribosomal protein S7p/S5e
Chain: N
Length: 130 amino acids
Theoretical weight: 14.15 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S8
Length: 130 amino acids
Theoretical weight: 14.15 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7W7 (Residues: 1-130; Coverage: 100%)
Pfam: Ribosomal protein S8
Chain: O
Length: 130 amino acids
Theoretical weight: 14.89 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S9/S16
Length: 130 amino acids
Theoretical weight: 14.89 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7X3 (Residues: 1-130; Coverage: 100%)
Pfam: Ribosomal protein S9/S16
Chain: P
Length: 103 amino acids
Theoretical weight: 11.76 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S10p/S20e
Length: 103 amino acids
Theoretical weight: 11.76 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7R5 (Residues: 1-103; Coverage: 100%)
Pfam: Ribosomal protein S10p/S20e
Chain: Q
Length: 129 amino acids
Theoretical weight: 13.87 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S11
Length: 129 amino acids
Theoretical weight: 13.87 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7R9 (Residues: 1-129; Coverage: 100%)
Pfam: Ribosomal protein S11
Chain: R
Length: 124 amino acids
Theoretical weight: 13.77 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S12/S23
Length: 124 amino acids
Theoretical weight: 13.77 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7S3 (Residues: 1-124; Coverage: 100%)
Pfam: Ribosomal protein S12/S23
Chain: S
Length: 101 amino acids
Theoretical weight: 11.61 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S14p/S29e
Length: 101 amino acids
Theoretical weight: 11.61 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0AG59 (Residues: 1-101; Coverage: 100%)
Pfam: Ribosomal protein S14p/S29e
Chain: T
Length: 89 amino acids
Theoretical weight: 10.29 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S15
Length: 89 amino acids
Theoretical weight: 10.29 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0ADZ4 (Residues: 1-89; Coverage: 100%)
Pfam: Ribosomal protein S15
Chain: U
Length: 82 amino acids
Theoretical weight: 9.21 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S16
Length: 82 amino acids
Theoretical weight: 9.21 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7T3 (Residues: 1-82; Coverage: 100%)
Pfam: Ribosomal protein S16
Chain: V
Length: 84 amino acids
Theoretical weight: 9.72 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S17
Length: 84 amino acids
Theoretical weight: 9.72 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0AG63 (Residues: 1-84; Coverage: 100%)
Pfam: Ribosomal protein S17
Chain: W
Length: 92 amino acids
Theoretical weight: 10.46 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S19
Length: 92 amino acids
Theoretical weight: 10.46 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7U3 (Residues: 1-92; Coverage: 100%)
Pfam: Ribosomal protein S19
Chain: X
Length: 118 amino acids
Theoretical weight: 13.13 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein S13/S18
Length: 118 amino acids
Theoretical weight: 13.13 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7S9 (Residues: 1-118; Coverage: 100%)
Pfam: Ribosomal protein S13/S18
Chain: Z
Length: 121 amino acids
Theoretical weight: 12.31 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
Pfam:
Length: 121 amino acids
Theoretical weight: 12.31 KDa
Source organism: Escherichia coli K-12
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7K2 (Residues: 1-121; Coverage: 100%)
Pfam:
Chain: b
Length: 85 amino acids
Theoretical weight: 9.15 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal L27 protein
Length: 85 amino acids
Theoretical weight: 9.15 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7L8 (Residues: 1-85; Coverage: 100%)
Pfam: Ribosomal L27 protein
Chain: c
Length: 78 amino acids
Theoretical weight: 9.03 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal L28 family
Length: 78 amino acids
Theoretical weight: 9.03 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
A0A1X3JA73 (Residues: 1-78; Coverage: 100%)
Pfam: Ribosomal L28 family
Chain: e
Length: 63 amino acids
Theoretical weight: 7.29 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Length: 63 amino acids
Theoretical weight: 7.29 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Chain: f
Length: 59 amino acids
Theoretical weight: 6.55 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Length: 59 amino acids
Theoretical weight: 6.55 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Chain: g
Length: 70 amino acids
Theoretical weight: 7.89 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L31
Length: 70 amino acids
Theoretical weight: 7.89 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7M9 (Residues: 1-70; Coverage: 100%)
Pfam: Ribosomal protein L31
Chain: h
Length: 273 amino acids
Theoretical weight: 29.92 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam:
Length: 273 amino acids
Theoretical weight: 29.92 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P60422 (Residues: 1-273; Coverage: 100%)
Pfam:
Chain: i
Length: 57 amino acids
Theoretical weight: 6.46 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Length: 57 amino acids
Theoretical weight: 6.46 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Chain: j
Length: 209 amino acids
Theoretical weight: 22.28 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L3
Length: 209 amino acids
Theoretical weight: 22.28 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P60438 (Residues: 1-209; Coverage: 100%)
Pfam: Ribosomal protein L3
Chain: k
Length: 55 amino acids
Theoretical weight: 6.39 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Length: 55 amino acids
Theoretical weight: 6.39 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Chain: l
Length: 201 amino acids
Theoretical weight: 22.12 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L4/L1 family
Length: 201 amino acids
Theoretical weight: 22.12 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
A1AGK6 (Residues: 1-201; Coverage: 100%)
Pfam: Ribosomal protein L4/L1 family
Chain: m
Length: 46 amino acids
Theoretical weight: 5.4 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L34
Length: 46 amino acids
Theoretical weight: 5.4 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
B7MGC4 (Residues: 1-46; Coverage: 100%)
Pfam: Ribosomal protein L34
Chain: n
Length: 179 amino acids
Theoretical weight: 20.33 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Length: 179 amino acids
Theoretical weight: 20.33 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Chain: o
Length: 65 amino acids
Theoretical weight: 7.31 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L35
Length: 65 amino acids
Theoretical weight: 7.31 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P0A7Q1 (Residues: 1-65; Coverage: 100%)
Pfam: Ribosomal protein L35
Chain: p
Length: 177 amino acids
Theoretical weight: 18.93 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L6
Length: 177 amino acids
Theoretical weight: 18.93 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
C3SR17 (Residues: 1-177; Coverage: 100%)
Pfam: Ribosomal protein L6
Chain: q
Length: 38 amino acids
Theoretical weight: 4.38 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L36
Length: 38 amino acids
Theoretical weight: 4.38 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
A0A0E2L017 (Residues: 1-38; Coverage: 100%)
Pfam: Ribosomal protein L36
Chain: r
Length: 149 amino acids
Theoretical weight: 15.79 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Length: 149 amino acids
Theoretical weight: 15.79 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Chain: s
Length: 142 amino acids
Theoretical weight: 16.05 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Length: 142 amino acids
Theoretical weight: 16.05 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Chain: t
Length: 123 amino acids
Theoretical weight: 13.57 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L14p/L23e
Length: 123 amino acids
Theoretical weight: 13.57 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
S1NW45 (Residues: 1-123; Coverage: 100%)
Pfam: Ribosomal protein L14p/L23e
Chain: u
Length: 144 amino acids
Theoretical weight: 15.01 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal proteins 50S-L15, 50S-L18e, 60S-L27A
Length: 144 amino acids
Theoretical weight: 15.01 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
A0A037Y8L6 (Residues: 1-144; Coverage: 100%)
Pfam: Ribosomal proteins 50S-L15, 50S-L18e, 60S-L27A
Chain: v
Length: 136 amino acids
Theoretical weight: 15.31 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L16p/L10e
Length: 136 amino acids
Theoretical weight: 15.31 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
P0ADY7 (Residues: 1-136; Coverage: 100%)
Pfam: Ribosomal protein L16p/L10e
Chain: w
Length: 127 amino acids
Theoretical weight: 14.39 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Length: 127 amino acids
Theoretical weight: 14.39 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Chain: x
Length: 117 amino acids
Theoretical weight: 12.79 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Length: 117 amino acids
Theoretical weight: 12.79 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Chain: y
Length: 115 amino acids
Theoretical weight: 13.16 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Length: 115 amino acids
Theoretical weight: 13.16 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
Chain: z
Length: 118 amino acids
Theoretical weight: 13.53 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
Pfam: Ribosomal protein L20
Length: 118 amino acids
Theoretical weight: 13.53 KDa
Source organism: Escherichia coli
Expression system: Escherichia coli
UniProt:
- Canonical:
B7MAS6 (Residues: 1-118; Coverage: 100%)
Pfam: Ribosomal protein L20
Name:
mRNA with 24 nt long spacer
Representative chains: 7
Length: 41 nucleotides
Theoretical weight: 12.91 KDa
Representative chains: 7
Length: 41 nucleotides
Theoretical weight: 12.91 KDa
Name:
E-site and P-site fMet-tRNA
Representative chains: A, B
Length: 76 nucleotides
Theoretical weight: 24.5 KDa
Rfam: tRNA
Representative chains: A, B
Length: 76 nucleotides
Theoretical weight: 24.5 KDa
Rfam: tRNA
Name:
16S ribosomal RNA
Representative chains: D
Length: 1542 nucleotides
Theoretical weight: 499.69 KDa
Rfam: Bacterial small subunit ribosomal RNA
Representative chains: D
Length: 1542 nucleotides
Theoretical weight: 499.69 KDa
Rfam: Bacterial small subunit ribosomal RNA
Name:
23S ribosomal RNA
Representative chains: a
Length: 2904 nucleotides
Theoretical weight: 941.64 KDa
Rfam: Bacterial large subunit ribosomal RNA
Representative chains: a
Length: 2904 nucleotides
Theoretical weight: 941.64 KDa
Rfam: Bacterial large subunit ribosomal RNA
Name:
5S ribosomal RNA
Representative chains: d
Length: 120 nucleotides
Theoretical weight: 38.79 KDa
Rfam: 5S ribosomal RNA
Representative chains: d
Length: 120 nucleotides
Theoretical weight: 38.79 KDa
Rfam: 5S ribosomal RNA