InterPro domain: IPR044509

This entry represents a group of plant CRIB domain-containing proteins including RIC2 and RIC4 from Arabidopsis. They belong to the RIC (ROP-interactive CRIB motif-containing protein) family. It has been shown that overexpression of RIC2 in tobacco germinating pollen reduces pollen tube elongation [ 1 ].

ROP1 and ROP6 have been shown to interact with RIC4, which promotes F-actin assembly. Together, they are involved in various processes of F-actin dynamics, cell growth, and plant/microbe interactions [ 2 ].

The RIC (ROP-interactive CRIB motif-containing protein) family members act as Rho GTPase (Rop) targets that function in distinct Rop signaling pathways [ 3 ]. RICs interact with multiple ROP GTPases via their conserved CRIB motif, and link ROP proteins to diverse target molecules that bind to their variable domains [ 3 ]. RICs share several consensus amino acid residues upstream of the CRIB motif and a consensus PSWMXDFK block downstream of the CRIB motif. Unlike other group members, members of group V, consisting of RIC4 and RIC2, lack the PSWMXDFK block and contain a relatively long N terminus in front of the CRIB motif and a short C terminus [ 4 ].

1. A genome-wide analysis of Arabidopsis Rop-interactive CRIB motif-containing proteins that act as Rop GTPase targets. Plant Cell 13, 2841-56
2. Arabidopsis ROP1 and ROP6 influence germination time, root morphology, the formation of F-actin bundles, and symbiotic fungal interactions. Mol Plant 6, 872-86
3. Small GTPases: versatile signaling switches in plants. Plant Cell 14 Suppl, S375-88