CHARACTERIZATION OF A GTP-BINDING PROTEIN IN THE ADP-RIBOSYLATION FACTOR SUBFAMILY FROM LEISHMANIA-TARENTOLAE

We report the cloning and characterization of a gene, LtARL, which enc odes a small GTP-binding protein, from the protozoan Leishmania tarent olae. Hybridization analysis of genomic DNA under high stringency cond itions indicates the single-copy nature of LtARL. LtARL is transcribed and yields a similar to 0.9 kb mRNA that is processed at the 5' end b y trans-splicing. When expressed in Escherichia coli, LtArl binds GTP with a low stoichiometry and in a phospholipid-independent manner. Bas ed on the greatest sequence identity with Homo sapiens Arl3 and lipid- independent binding of guanine nucleotides we designate this gene LtAR L and the encoded protein LtArl. (C) 1998 Elsevier Science B.V. All ri ghts reserved.