Domain

Major sperm protein (MSP) domain (IPR000535)

Short name: MSP_dom

Domain relationships

  • PapD-like (IPR008962)
    • Major sperm protein (MSP) domain (IPR000535)

Description

Nematode sperm are unusual amoeboid cells in which motility is not based on actin, but instead on the major sperm protein (MSP). MSP is a dimeric molecule that polymerises to form non-polar filaments constructed from two helical subfilaments that wind round one another. The filaments then assemble into larger macromolecular assemblies called fibre complexes. MSP is a small (~14 kDa) basic protein typically encoded by a multigene family of up to 28 members [PMID: 8913307, PMID: 12051923, PMID: 9878374, PMID: 9641981]. An about 120-amino acid domain similar to MSP has been found in other proteins, including:

  • Animal Vesicle-Associated Membrane Protein-associated (VAMP-associated) protein family of 33 kDa (VAP33). VAP33 is required for neurotransmitter release. It binds to the v-SNARE synaptobrevin/VAMP which is associated with vesicle fusion. VAP33 has a two-domain structure with its N terminus being highly homologous to MSP, whereas its C terminus is based on a putative alpha-helical coiled-coil combined with an extremly hydrophobic membrane-attachment region [PMID: 9920726].
  • Nicotiana plumbaginifolia VAP27, a VAP33 homologue. It interacts with the resistance protein Cf9 [PMID: 10733941].
  • Yeast inositol regulator SCS2, a VAP33 homologue. It is C-terminally anchored to the endoplasmic reticulum [PMID: 9537365].

The MSP polypeptide chain has an immunoglobulin-like fold based on a seven- stranded beta sandwich measuring approximately 15 A x 20 A x 45 A and having opposing three-stranded and four-stranded beta sheets [PMID: 8913307].

This entry represents the MSP domain.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
Pfam
PROSITE profiles