Mss4 (IPR007515)

Short name: Mss4

Family relationships



MSS4 (mammalian suppressor of Sec4) is an evolutionarily highly conserved protein, which is expressed in all mammalian tissues. Although it was first proposed to function as a guanine exchange factor (GEF) for Rab GTPases, it was soon described as a quite inefficient GEF and was thus suggested to function rather as a chaperone, protecting nucleotide free Rabs from degradation, than as a GEF [PMID: 22495352].

The structure of MSS4 revealed a mostly beta fold stabilized by a Zn(2+) ion coordinated by cysteine residues from two CxxC motifs. The fold of the MSS4 domain consists of a central beta sheet (betaG-betaK) flanked by a beta hairpin (betaB-betaC) on one side and a small variable sheet on the other. A single Zn(2+) ion, coordinated by the thiol groups of cysteine residues from two CxxC motifs located in the betaB-betaC and betaI-betaJ loops, appears to play an important structural role by reinforcing the hydrophobic core formed by the betaB-betaC hairpin, the betaG-betaH loop, and the central beta sheet [PMID: 7651540, PMID: 11258916, PMID: 16541104].

GO terms

Biological Process

GO:0007264 small GTPase mediated signal transduction

Molecular Function

GO:0005085 guanyl-nucleotide exchange factor activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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