Seroatlas · Human Serome Atlas

SPMIP9

Protein SPMIP9

Also known as: C2orf51, FLJ25369, SMIP9_HUMAN, TEX37, TSC21

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

Protein identityUniProt · HPA

UniProt accession: Q96LM6
Gene: SPMIP9
Ensembl: ENSG00000172073
Chromosome: 2
Canonical length: 180 aa
Protein class: Predicted intracellular proteins
Subcellular location: Cytosol,Connecting piece,Mid piece,Principal piece,End piece

OverviewNCBI Gene

Predicted to be involved in flagellated sperm motility. Located in cytoplasm. [provided by Alliance of Genome Resources, Jul 2025]

Canonical amino-acid sequenceUniProt

180 residues, UniProt reviewed canonical sequence.

>Q96LM6|SPMIP9
     1  MAGVKYPGQD PVDLDIYQSS HMVDYQPYRK HKYSRVTPQE QAKLDAQLRD KEFYRPIPNP
    61  NPKLTDGYPA FKRPHMTAKD LGLPGFFPSQ EHEATREDER KFTSTCHFTY PASHDLHLAQ
   121  GDPNQVLQSA DFPCLVDPKH QPAAEMAKGY LLLPGCPCLH CHIVKVPILN RWGPLMPFYQ

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SPMIP9 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): 0.61
Highest tissue expression: 81 nTPM

Expression across tissuesHPA

Tissue

testis: 81 nTPM
placenta: 0.1 nTPM
adipose tissue: 0 nTPM
adrenal gland: 0 nTPM
amygdala: 0 nTPM
appendix: 0 nTPM

Single-cell type

late spermatids: 4,157 nCPM
early spermatids: 1,114 nCPM
late primary spermatocytes: 35 nCPM
undifferentiated spermatogonia: 9.5 nCPM
sertoli cells: 8.4 nCPM
leydig cells: 5.3 nCPM

Immune cell

basophil: 0 nTPM
classical monocyte: 0 nTPM
eosinophil: 0 nTPM
gdT-cell: 0 nTPM
intermediate monocyte: 0 nTPM
MAIT T-cell: 0 nTPM

Brain region

cerebral cortex: 0.3 nTPM
hypothalamus: 0.2 nTPM
basal ganglia: 0.1 nTPM
medulla oblongata: 0.1 nTPM
midbrain: 0.1 nTPM
amygdala: 0 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): 1.91
gnomAD pLI: 0
DepMap mean gene effect: -0.11
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).

OntologyGO

Biological processes

flagellated sperm motility

Cellular components

Protein domainsUniProt · Pfam · InterPro

Sperm microtubule inner protein 9
TSC21 family

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads SPMIP9 as an antibody target. Whether an autoantibody or antibody against SPMIP9 could matter depends on whether native SPMIP9 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

SPMIP9 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 SPMIP9 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

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