Seroatlas · Human Serome Atlas

SPMIP4

Sperm-associated microtubule inner protein 4

Also known as: C7orf31, SMIP4_HUMAN

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

Protein identityUniProt · HPA

UniProt accession: Q8N865
Gene: SPMIP4
Ensembl: ENSG00000153790
Chromosome: 7
Canonical length: 590 aa
Protein class: Predicted intracellular proteins
Subcellular location: Nucleoplasm,Mitochondria,Cytosol

OverviewNCBI Gene

Located in centrosome. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

590 residues, UniProt reviewed canonical sequence.

>Q8N865|SPMIP4
     1  MEVIHGRPYC CRELEGADIL SNTFYSNELH NPLQTVTRPT ASEDRYQELR ESLQQCRLPW
    61  GAEREYGGII PISLPEDHRP KYEPPRVMGK GHQHYGFGGE TWPRKLPVEQ FYYLTQNKKS
   121  DVYGNDSLIP KPPNSTVGEI CLPYPIEHPY HTHICRGAMF PTFTSPEDLY TGIKARTQQP
   181  FPPTVPTKAY DSTVLKTRGN PYRYELIDIP MDSKKKALTW PGQGVYYDFP RGVEKNKPVF
   241  YPKPPKTFAP NTSLNSWDPI CSAKEANIQR NLERSHWLTS YTHDFTGLGP MDPLELDDYH
   301  EKMVAELTRK IGFDPEPQEK FHPVFKPPRP LEGRIARLIQ NRRSLEAIVQ QRPRSCPDCT
   361  PRVLCNFHTF VPSSKEMVAL SDNIPAGVTH KNQDIEEKII EEQSLLSTYE LPSCYPTKDL
   421  TSIYDIKPFP KITDTKKTED LYWRQQSLKT QPTPYCKPDH WIHYENLKSP LRDQYNMCPD
   481  PVSLSKPSVL QNKQDTEAFT LEHFLSKPEE ELFLNMENNE ETRPVLGWIP RAGVTKPQTN
   541  LLELKNSFSK TGAQKRFHKS ILEDHKDLRD NEHSGMKHQF YGHNSYYFYN

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SPMIP4 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): 0.57
Highest tissue expression: 61 nTPM

Expression across tissuesHPA

Tissue

testis: 61 nTPM
colon: 6.4 nTPM
adrenal gland: 6.2 nTPM
ovary: 4.5 nTPM
rectum: 4.3 nTPM
stomach: 4.2 nTPM

Single-cell type

late spermatids: 1,448 nCPM
early spermatids: 539 nCPM
late primary spermatocytes: 127 nCPM
retinal pigment epithelial cells: 81 nCPM
adrenal cortex cells: 35 nCPM
early primary spermatocytes: 28 nCPM

Immune cell

plasmacytoid DC: 1.9 nTPM
memory B-cell: 1 nTPM
NK-cell: 1 nTPM
T-reg: 1 nTPM
naive CD4 T-cell: 0.9 nTPM
eosinophil: 0.8 nTPM

Brain region

cerebellum: 7.4 nTPM
white matter: 5.7 nTPM
hypothalamus: 5.6 nTPM
medulla oblongata: 5.6 nTPM
basal ganglia: 5 nTPM
cerebral cortex: 4.8 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
DepMap mean gene effect: 0.12
DepMap dependency class: none

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 8% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Cellular components

centrosome

Protein domainsUniProt · Pfam · InterPro

Sperm-associated microtubule inner protein 4
Sperm-associated microtubule inner protein 4

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads SPMIP4 as an antibody target. Whether an autoantibody or antibody against SPMIP4 could matter depends on whether native SPMIP4 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SPMIP4 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 SPMIP4 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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