Guanylate Binding Protein 5 (GBP5)

Like all GBPs, GBP5 has a conserved N-terminal globular GTP-binding domain containing 2 consensus sequences and a third T(L/V)RD sequence not found in other GTPases. Like GBP1 and GBP2, GBP5 has a C-terminal CaaX isoprenylation motif. EST database analysis indicated wide expression of GBP5 in human tissues. Immunofluorescence analysis demonstrated cytoplasmic expression of GBP5. Irrespective of stimulation, GBP5 was constitutively expressed in the Golgi apparatus.The GBP5ta splice variant lacks exons 11 and 12 leading to C-terminal deletion of 97 amino acids and loss of a putative isoprenylation site. The GBP5a variant lacks the noncoding exon 2.The deduced 586-amino acid protein has a predicted molecular mass of 67 kD and contains a guanylate-binding site composed of 3 motifs.