ADP Ribosylation Factor Like Protein 3 (ARL3)

The predicted 182-amino acid ARL3 protein shares 97% amino acid identity with rat Arl3 and 43% identity with human ARF1. Like the ARFs, ARL3 has a glycine at position 2, the site of N myristoylation, and lacks cysteine residues near the C terminus, which are found in other members of the RAS family. Northern blot analysis detected a 1-kb ARL3 transcript in all tissues tested, with highest expression in heart and lung, and lower expression in brain, liver, kidney, ovary, and testis. A 5.5-kb transcript was also detected in most tissues, with highest expression in brain. Immunoblot analysis detected ARL3 in human tumor cell lines but not in normal rodent cells. Although ARL3 binds GTP, it is devoid of activity in the cholera toxin-dependent ADP-ribosylation of Gs, and is therefore classified as an ARF-like protein.