Seroatlas · Human Serome Atlas

TMEM121B

Transmembrane protein 121B

Also known as: CECR6, T121B_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: Q9BXQ6
Gene: TMEM121B
Ensembl: ENSG00000183307
Chromosome: 22
Canonical length: 578 aa
Protein class: Predicted membrane proteins
Subcellular location: Nucleoplasm,Vesicles,Plasma membrane

OverviewNCBI Gene

No narrative summary is available for TMEM121B in this catalog release; identity and structured annotations are shown without generated factual claims.

Canonical amino-acid sequenceUniProt

578 residues, UniProt reviewed canonical sequence.

>Q9BXQ6|TMEM121B
     1  MRPALGHPRS VSSASGSFPP PPAAARLQPL FLRGGSFRGR RGSGDSSTST STSRGGGGGR
    61  RGGGGGSPSS STGAEREDDD ESLSVSKPLV PNAALLGPPA QVGAPAGPAP VAFSSSAATS
   121  SSTSTPTSSC SMTAADFGGG AAAGAVGGPG SRSAGGAGGT GTGSGASCCP CCCCCGCPDR
   181  PGRRGRRRGC APSPRCRWGY QALSVVLLLA QGGLLDLYLI AVTDLYWCSW IATDLVVVVG
   241  WAIFFAKNSR GRRGGAASGA HNHHLHHHHA APPLHLPAPS AATAGAKARG ARGGAGGAGG
   301  GLGAAAAAGE FAFAYLAWLI YSIAFTPKVV LILGTSILDL IELRAPFGTT GFRLTMALSV
   361  PLLYSLVRAI SEAGAPPGSA GPLLLQPQRH RAAGCFLGTC LDLLDSFTLV ELMLEGRVPL
   421  PAHLRYLLIA VYFLTLASPV LWLYELNAAA AAAASWGQAS GPGSCSRLLR LLGGCLVDVP
   481  LLALRCLLVV SYQQPLSIFM LKNLFFLGCR GLEALEGCWD RGNRASPSRA RGGYGAPPSA
   541  PPPPPPPPQG GSQLGHCISE NEGGAHGYVN TLAVASQN

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against TMEM121B 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: Unknown
Secreted: No
Transmembrane segments: 0
Mean surface accessibility (rSASA): 0.54
Highest tissue expression: 8.4 nTPM

Expression across tissuesHPA

Tissue

cerebral cortex: 8.4 nTPM
basal ganglia: 6.5 nTPM
cerebellum: 6.5 nTPM
prostate: 6.2 nTPM
hippocampal formation: 5.9 nTPM
amygdala: 4.2 nTPM

Single-cell type

early spermatids: 15 nCPM
neutrophils: 12 nCPM
late spermatids: 11 nCPM
oligodendrocyte progenitor cells: 8 nCPM
microglia: 6.3 nCPM
brain excitatory neurons: 6 nCPM

Immune cell

neutrophil: 1.7 nTPM
classical monocyte: 1.1 nTPM
intermediate monocyte: 0.4 nTPM
myeloid DC: 0.2 nTPM
total PBMC: 0.2 nTPM
basophil: 0 nTPM

Brain region

hippocampal formation: 17 nTPM
cerebral cortex: 15 nTPM
basal ganglia: 15 nTPM
amygdala: 9.9 nTPM
white matter: 9.6 nTPM
hypothalamus: 9.1 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): 0.57
gnomAD pLI: 0.7
DepMap mean gene effect: -0.03
DepMap dependency class: selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 3% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

Protein domainsUniProt · Pfam · InterPro

CECR6/TMEM121 family
CECR6/TMEM121 family
Cat eye syndrome critical region protein 6

KeywordsUniProt

Phosphoprotein

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads TMEM121B as an antibody target. Whether an autoantibody or antibody against TMEM121B could matter depends on whether native TMEM121B is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

TMEM121B 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 TMEM121B as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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