Identification and Characterization of Agv1, a Pre-Metazoan Arf GAP: A Dissertation

Human immunodeficiency virus type 1 (HIV-1) is a member of the lentivirus subfamily of retroviruses. HIV-1 expresses multiple genes from a single provirus by alternative splicing. Early in viral expression, fully spliced 2-kb viral RNA is exported from the nucleus and encodes the viral regulatory protein, Rev, which is essential for nuclear transport of partially spliced and unspliced genomic-length RNA. Rev binds to an RNA structural element called the Rev response element (RRE) and mediates nuclear export through the leucine-rich nuclear export signal (NES) pathway. The human Rev Interacting Protein (hRIP) interacts specifically with the Rev NES. Rev NES mutants that are unable to export Rev-dependent RNAs are also unable to bind to hRIP. The hRIP cDNA encodes a 562 amino acid protein containing an N-terminal zinc finger with homology to Arf GAP domains, a central serine and threonine rich region, and Cterminal phenylalanine-glycine (FG) repeats characteristic of nucleoporins. To identify an hRIP ortholog in a genetically tractable organism, we performed database searches using the N-terminal zinc finger of hRIP. Using this approach, we identified a novel gene in Schizosaccharomyces pombe. Alignment of the entire reading frame of the putative ortholog with hRIP indicates similarity with the serine/threonine rich region and with the FG repeats,