Seroatlas · Human Serome Atlas

SRM

Spermidine synthase

Also known as: SPEE_HUMAN, SPS1, SRML1

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

Protein identityUniProt · HPA

UniProt accession
P19623
Gene
SRM
Ensembl
ENSG00000116649
Chromosome
1
Canonical length
302 aa
Protein class
Enzymes, Metabolic proteins, Predicted intracellular proteins
Subcellular location
Nucleoplasm,Cytosol
Quaternary structure
Homotetramer

OverviewNCBI Gene

The polyamines putrescine, spermine, and spermidine are ubiquitous polycationic mediators of cell growth and differentiation. Spermidine synthase is one of four enzymes in the polyamine-biosynthetic pathway and carries out the final step of spermidine biosynthesis. This enzyme catalyzes the conversion of putrescine to spermidine using decarboxylated S-adenosylmethionine as the cofactor. [provided by RefSeq, Jul 2008]

Canonical amino-acid sequenceUniProt

302 residues, UniProt reviewed canonical sequence.

>P19623|SRM
     1  MEPGPDGPAA SGPAAIREGW FRETCSLWPG QALSLQVEQL LHHRRSRYQD ILVFRSKTYG
    61  NVLVLDGVIQ CTERDEFSYQ EMIANLPLCS HPNPRKVLII GGGDGGVLRE VVKHPSVESV
   121  VQCEIDEDVI QVSKKFLPGM AIGYSSSKLT LHVGDGFEFM KQNQDAFDVI ITDSSDPMGP
   181  AESLFKESYY QLMKTALKED GVLCCQGECQ WLHLDLIKEM RQFCQSLFPV VAYAYCTIPT
   241  YPSGQIGFML CSKNPSTNFQ EPVQPLTQQQ VAQMQLKYYN SDVHRAAFVL PEFARKALND
   301  VS

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against SRM 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)
0.23
Highest tissue expression
184 nTPM

Expression across tissuesHPA

Tissue

  • pancreas: 184 nTPM
  • skeletal muscle: 123 nTPM
  • heart muscle: 84 nTPM
  • basal ganglia: 83 nTPM
  • blood vessel: 76 nTPM
  • amygdala: 75 nTPM

Single-cell type

  • plasma cells: 336 nCPM
  • breast myoepithelial cells: 285 nCPM
  • esophageal basal cells: 222 nCPM
  • extravillous trophoblasts: 207 nCPM
  • pancreatic acinar cells: 190 nCPM
  • migrating cytotrophoblasts: 182 nCPM

Immune cell

  • memory B-cell: 13 nTPM
  • naive B-cell: 11 nTPM
  • plasmacytoid DC: 11 nTPM
  • MAIT T-cell: 11 nTPM
  • naive CD8 T-cell: 10 nTPM
  • memory CD8 T-cell: 9.3 nTPM

Brain region

  • midbrain: 73 nTPM
  • thalamus: 69 nTPM
  • hippocampal formation: 67 nTPM
  • hypothalamus: 65 nTPM
  • cerebral cortex: 63 nTPM
  • basal ganglia: 61 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
0.23
gnomAD missense Z
2.55
DepMap mean gene effect
-0.18
DepMap dependency class
selective

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 5% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

Antibody and autoantibody relevanceSeroatlas analysis

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

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

Canonical record: https://seroatlas.com/gene/SRM. Study-independent annotations aggregated from UniProt, Human Protein Atlas, PubMed, IEDB, Pfam, InterPro, Gene Ontology, AlphaFold, gnomAD, DepMap, ClinVar, TCGA. Catalog release seroatlas-reviewed-human-uniprot-20260313.

Seroatlas is the reference for exploring autoantibody and antibody serology at the human-protein level: the autoreactome and human serome, multiplex serology (HuProt, HuScan, VirScan, PhIP-Seq).

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