Recombinant Human VG5Q Protein, CF

VG5Q, also known as AGGF1, was identified by its association with Klippel-Trenaunay syndrome (KTS), a congenital vascular morphogenesis disorder (1 - 3). Two genetic alterations found in KTS lead to aberrant expression or function of VG5Q: a chromosomal translocation that falls within the VG5Q promoter and a glutamate to lysine point mutation at position 133 (1). The human VG5Q cDNA encodes a 714 amino acid (aa) precursor with a coiled coil domain, an FHA domain, a G-patch domain, and an OCRE domain. FHA domains bind phosphorylated threonine and tyrosine residues (4, 5). G-patch and OCRE motif-containing proteins associate with RNA and are implicated in RNA metabolism (6, 7). Two splice variants (109 aa and 176 aa) of human VG5Q have C-terminal deletions and contain alternate sequences at their C-termini. The FHA, G-patch, and OCRE domains are absent in both of these splice variants. Human VG5Q shares 78% and 89% aa identity with mouse and canine VG5Q, respectively. Bovine VG5Q has a C-terminal truncation following position 294 but shares 85% aa identity with the corresponding region of human VG5Q. VG5Q is expressed by vascular endothelial cells in many tissues (1). It appears to be secreted and promotes endothelial cell proliferation following interactions with endothelial cell surfaces (1). VG5Q also directly interacts with TWEAK (1), a TNF superfamily ligand with angiogenic properties (8). The FHA, G-patch, and OCRE domains of VG5Q suggest additional intracellular functions.