CLONING OF A NOVEL MEMBER (ARL5) OF THE ARF-FAMILY OF RAS-RELATED GTPASES

A novel ras-related GTPase with a unique structure was cloned by PCR-a mplification with degenerate primers and screening of a rat fat cell c DNA library. The deduced amino acid sequence of the cDNA comprises all 6 GTP binding motifs which are conserved in Ras-related GTPases. The sequence is similar to that of ADP-ribosylation factors (ARF), and sho ws several structural features typical for the ARF-family. Because its closest relative is the GTPase ARL1 (49% identical amino acids, 54% i dentical nucleotides within the coding region), the protein was design ated ARL5 (ARF-like protein 5). Low amounts of mRNA were found in most rat tissues examined (heart, skeletal muscle, fat, liver, kidney, lun g, spleen, intestine, testis, and thymus) with highest levels in brain , intestine, and thymus.