Seroatlas · Human Serome Atlas

MRPS18B

Small ribosomal subunit protein mS40

Also known as: C6orf14, HSPC183, MRPS18-2, PTD017, RT18B_HUMAN

Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene

Protein identityUniProt · HPA

UniProt accession: Q9Y676
Gene: MRPS18B
Ensembl: ENSG00000204568
Chromosome: 6
Canonical length: 258 aa
Protein class: Predicted intracellular proteins, Ribosomal proteins
Subcellular location: Cell Junctions,Mitochondria

OverviewNCBI Gene

Mammalian mitochondrial ribosomal proteins are encoded by nuclear genes and help in protein synthesis within the mitochondrion. Mitochondrial ribosomes (mitoribosomes) consist of a small 28S subunit and a large 39S subunit. They have an estimated 75% protein to rRNA composition compared to prokaryotic ribosomes, where this ratio is reversed. Another difference between mammalian mitoribosomes and prokaryotic ribosomes is that the latter contain a 5S rRNA. Among different species, the proteins comprising the mitoribosome differ greatly in sequence, and sometimes in biochemical properties, which prevents easy recognition by sequence homology. This gene encodes a 28S subunit protein that belongs to the ribosomal protein S18P family. The encoded protein is one of three that has significant sequence similarity to bacterial S18 proteins. The primary sequences of the three human mitochondrial S18 proteins are no more closely related to each other than they are to the prokaryotic S18 proteins. Pseudogenes corresponding to this gene are found on chromosomes 1q and 2q. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

258 residues, UniProt reviewed canonical sequence.

>Q9Y676|MRPS18B
     1  MAASVLNTVL RRLPMLSLFR GSHRVQVPLQ TLCTKAPSEE DSLSSVPISP YKDEPWKYLE
    61  SEEYQERYGS RPVWADYRRN HKGGVPPQRT RKTCIRRNKV VGNPCPICRD HKLHVDFRNV
   121  KLLEQFVCAH TGIIFYAPYT GVCVKQHKRL TQAIQKARDH GLLIYHIPQV EPRDLDFSTS
   181  HGAVSATPPA PTLVSGDPWY PWYNWKQPPE RELSRLRRLY QGHLQEESGP PPESMPKMPP
   241  RTPAEASSTG QTGPQSAL

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against MRPS18B can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.

Antibody reachability: Intracellular
Secreted: No
Transmembrane segments: 0
Mean surface accessibility (rSASA): 0.5
Highest tissue expression: 214 nTPM

Expression across tissuesHPA

Tissue

tongue: 214 nTPM
skeletal muscle: 194 nTPM
heart muscle: 116 nTPM
liver: 95 nTPM
kidney: 74 nTPM
parathyroid gland: 70 nTPM

Single-cell type

oligodendrocytes: 21 nCPM
papillary tip epithelial cells: 18 nCPM
renal collecting duct principal cells: 18 nCPM
loop of henle epithelial cells: 17 nCPM
distal convoluted tubule cells: 16 nCPM
proximal tubule cells: 15 nCPM

Immune cell

memory B-cell: 154 nTPM
naive B-cell: 141 nTPM
naive CD4 T-cell: 130 nTPM
NK-cell: 121 nTPM
T-reg: 108 nTPM
total PBMC: 108 nTPM

Brain region

white matter: 44 nTPM
cerebellum: 42 nTPM
thalamus: 42 nTPM
medulla oblongata: 41 nTPM
spinal cord: 39 nTPM
basal ganglia: 39 nTPM

Genetic constraint and essentialitygnomAD · DepMap

Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.

gnomAD LOEUF (loss-of-function intolerance): 1.02
gnomAD pLI: 0
gnomAD missense Z: -0.16
DepMap mean gene effect: -0.45
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 25% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

structural constituent of ribosome

Cellular components

Protein domainsUniProt · Pfam · InterPro

Small ribosomal subunit protein bS18
Small ribosomal subunit protein bS18 superfamily
Ribosomal protein S18
Small ribosomal subunit protein mS40

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of MRPS18B in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads MRPS18B as an antibody target. Whether an autoantibody or antibody against MRPS18B could matter depends on whether native MRPS18B is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

MRPS18B is annotated as predominantly intracellular. Intracellular proteins are common autoantibody markers, becoming visible to the immune system after cell injury or altered processing, but are usually markers of disease rather than direct drivers.

Annotation status

The present source text does not explicitly label MRPS18B as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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