High impact information on ARHGEF9

• Our data suggest that collybistin II regulates the membrane deposition of gephyrin by activating a GTPase of the Rho/Rac family [1].
• Identification and characterization of hPEM-2, a guanine nucleotide exchange factor specific for Cdc42 [2].
• Highlighting its central role in this receptor anchoring scaffold, gephyrin interacts with a number of proteins, including the neurospecific guanine nucleotide exchange factor collybistin [3].
• The Crystal Structure of Cdc42 in Complex with Collybistin II, a Gephyrin-interacting Guanine Nucleotide Exchange Factor [3].
• The predicted amino acid sequence suggested that PEM-2 contains a signal for nuclear localization, an src homology 3 (SH3) domain, and a consensus sequence of the CDC24 family guanine nucleotide dissociation stimulators (GDSs) [4].

Biological context of ARHGEF9

• The presence of the SH3 domain negatively regulates the ability of collybistin to translocate gephyrin to submembrane microaggregates in transfected mammalian cells [5].
• We report the characterization of several new variants of collybistin, which are created by alternative splicing of exons encoding an N-terminal src homology 3 (SH3) domain and three alternate C termini (CB1, CB2, and CB3) [5].
• The clinical manifestation of this collybistin missense mutation may result, at least in part, from mislocalization of gephyrin and a major GABA(A) receptor subtype [5].

Anatomical context of ARHGEF9

• Glycine receptors (GlyRs) and specific subtypes of GABA(A) receptors are clustered at synapses by the multidomain protein gephyrin, which in turn is translocated to the cell membrane by the GDP-GTP exchange factor collybistin [5].

Associations of ARHGEF9 with chemical compounds

• Co-expression of collybistin II with gephyrin induced the formation of submembrane gephyrin aggregates that accumulate hetero-oligomeric glycine receptors [1].

Physical interactions of ARHGEF9

• Furthermore, in vitro gephyrin bound simultaneously to both collybistin and the GlyR beta-subunit binding motif [6].

Other interactions of ARHGEF9

• Here we describe two splice variants of a novel gephyrin-binding protein, termed collybistin I and II, which belong to the family of dbl-like GDP/GTP exchange factors (GEFs) [1].
• Expression of ARHGEF4 is restricted to brain and the encoded protein shows homology to collybistin [7].

References