Seroatlas · Human Serome Atlas

MASP1

Mannan-binding lectin serine protease 1

Also known as: CRARF, MAP-1, Map44, MASP, MASP-3, MASP1_HUMAN, PRSS5

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

Protein identityUniProt · HPA

UniProt accession
P48740
Gene
MASP1
Ensembl
ENSG00000127241
Chromosome
3
Canonical length
699 aa
Protein class
Disease related genes, Enzymes, Human disease related genes, Plasma proteins, Potential drug targets, Predicted intracellular proteins, Predicted secreted proteins
Subcellular location
Nucleoplasm,Cytosol
Secretome location
Secreted to blood
Quaternary structure
Homodimer

OverviewNCBI Gene

This gene encodes a serine protease that functions as a component of the lectin pathway of complement activation. The complement pathway plays an essential role in the innate and adaptive immune response. The encoded protein is synthesized as a zymogen and is activated when it complexes with the pathogen recognition molecules of lectin pathway, the mannose-binding lectin and the ficolins. This protein is not directly involved in complement activation but may play a role as an amplifier of complement activation by cleaving complement C2 or by activating another complement serine protease, MASP-2. The encoded protein is also able to cleave fibrinogen and factor XIII and may may be involved in coagulation. A splice variant of this gene which lacks the serine protease domain functions as an inhibitor of the complement pathway. Alternate splicing results in multiple transcript variants.[provided by RefSeq, Apr 2010]

Canonical amino-acid sequenceUniProt

699 residues, UniProt reviewed canonical sequence.

>P48740|MASP1
     1  MRWLLLYYAL CFSLSKASAH TVELNNMFGQ IQSPGYPDSY PSDSEVTWNI TVPDGFRIKL
    61  YFMHFNLESS YLCEYDYVKV ETEDQVLATF CGRETTDTEQ TPGQEVVLSP GSFMSITFRS
   121  DFSNEERFTG FDAHYMAVDV DECKEREDEE LSCDHYCHNY IGGYYCSCRF GYILHTDNRT
   181  CRVECSDNLF TQRTGVITSP DFPNPYPKSS ECLYTIELEE GFMVNLQFED IFDIEDHPEV
   241  PCPYDYIKIK VGPKVLGPFC GEKAPEPIST QSHSVLILFH SDNSGENRGW RLSYRAAGNE
   301  CPELQPPVHG KIEPSQAKYF FKDQVLVSCD TGYKVLKDNV EMDTFQIECL KDGTWSNKIP
   361  TCKIVDCRAP GELEHGLITF STRNNLTTYK SEIKYSCQEP YYKMLNNNTG IYTCSAQGVW
   421  MNKVLGRSLP TCLPVCGLPK FSRKLMARIF NGRPAQKGTT PWIAMLSHLN GQPFCGGSLL
   481  GSSWIVTAAH CLHQSLDPED PTLRDSDLLS PSDFKIILGK HWRLRSDENE QHLGVKHTTL
   541  HPQYDPNTFE NDVALVELLE SPVLNAFVMP ICLPEGPQQE GAMVIVSGWG KQFLQRFPET
   601  LMEIEIPIVD HSTCQKAYAP LKKKVTRDMI CAGEKEGGKD ACAGDSGGPM VTLNRERGQW
   661  YLVGTVSWGD DCGKKDRYGV YSYIHHNKDW IQRVTGVRN

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against MASP1 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
Cell surface
Secreted
No
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.28
Highest tissue expression
172 nTPM

Expression across tissuesHPA

Tissue

  • liver: 172 nTPM
  • heart muscle: 109 nTPM
  • cervix: 101 nTPM
  • endometrium: 81 nTPM
  • vagina: 60 nTPM
  • colon: 55 nTPM

Single-cell type

  • hepatocytes: 109 nCPM
  • hepatic stellate cells: 90 nCPM
  • decidual stromal cells: 83 nCPM
  • astrocytes: 62 nCPM
  • cardiomyocytes: 61 nCPM
  • fibro-adipogenic progenitors: 53 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

  • white matter: 61 nTPM
  • hypothalamus: 53 nTPM
  • spinal cord: 43 nTPM
  • medulla oblongata: 37 nTPM
  • midbrain: 30 nTPM
  • thalamus: 26 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about MASP1.

Disease | AllUniProt

Conditions MASP1 is implicated in, by any mechanism.

Disease | GeneticClinVar

26 pathogenic / likely-pathogenic of 406 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

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)
0.98
gnomAD pLI
0
gnomAD missense Z
-0.16
DepMap mean gene effect
0.08
DepMap dependency class
none

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 4% 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

InteractionsUniProt · HPA

Protein binding partners of MASP1 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 MASP1 as an antibody target. Whether an autoantibody or antibody against MASP1 could matter depends on whether native MASP1 is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

MASP1 is annotated at the cell surface, where native MASP1 is exposed to circulating antibodies and is a prime autoantibody target that could block, deplete, or overstimulate it.

Annotation status

The present source text does not explicitly label MASP1 as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/MASP1. 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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