Mss4 (IPR007515)

Short name: Mss4

Overlapping homologous superfamilies

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