ephexin-1 (Eph-interacting exchange protein, neuronal guanine nucleotide exchange factor, NGEF)

Function

• acts as a guanine nucleotide exchange factor (GEF)
  • differentially activates the GTPases RHOA, RAC1 & CDC42
• axon guidance regulating ephrin-induced growth cone collapse
• upon activation by ephrin through EPHA4, the GEF activity switches toward RHOA resulting in its activation
• activated RHOA promotes cone retraction at the expense of RAC1- & CDC42-stimulated growth cone extension
• interacts with EPHA4 via DH domain & PH domain
• Src-dependent phosphorylation at Tyr-179 upon EPHA4 activation increases the guanine exchange factor activity toward RHOA

Structure

• contains 1 DH domain (DBL-homology domain)
• contains 1 PH domain.
• contains 1 SH3 domain

Compartment

• cytoplasm, membranes
• localizes to axonal growth cones

Alternative splicing

named isoforms=2

Expression

• expressed in brain specifically in caudate nucleus > amygdala, hippocampus
• also expressed in lung

More general terms

• ephexin (eph interacting exchange factor)

Database

• OMIM: https://mirror.omim.org/entry/605991
• UniProt: http://www.uniprot.org/uniprot/Q8N5V2.html