A family of guanine nucleotide exchange factors (GEFs) for ADP-ribosylation factor (ARF) GTPases. Cytohesin-1 (PH, SEC7 and coiled-coil domain-containing protein-1, SEC7 homologue B2–1, 398 aa) is ubiquitous, and acts on ARF1 and ARF5. Cytohesin-2 (ARF nucleotide-binding site opener, ARNO, 400 aa) acts on ARF1, ARF3, and ARF6. Cytohesin-3 (general receptor of phosphoinositides 1, Grp-1, 400 aa) acts on ARF1 and binds with high affinity to the inositol head group of phosphotidylinositol 3,4,5-trisphosphate via its PH domain. Cytohesin-4 (394 aa) is found predominantly in peripheral blood leucocytes. Cytohesin-interacting protein (359 aa) is a scaffolding and modulator protein that binds to cytohesin-1 and modifies the activation of ARF.
Subjects: Medicine and Health.