Ras Related GTP Binding Protein B (RRAGB)

Ragb bound a nonhydrolyzable analog of GTP, but that it lacked intrinsic GTPase activity. While Ragb(l) did not bind GTP, deletion of the 84-bp insertion in Ragb(l) permitted GTP binding.The full-length 374-amino acid RAGB(L) protein shares similarity with RAS (HRAS) and high similarity with RAGA. It contains phosphate/magnesium-binding motifs PM1, PM2, and PM3, and guanine-nucleotide-binding motifs G1 and G2. RAGB(L) has a 28-codon insertion relative to the shorter protein, RAGB(S), between PM2 and PM3. The N terminus of RAGB contains a 33-amino acid extension relative to RAGA. Northern blot analysis detected weak expression of 2 transcripts in rat brain, testis, adrenal gland, and thymus. PCR analysis revealed ubiquitous expression of rat Ragb(s), but only the long variant in brain.