The Ras guanine nucleotide exchange factor CDC25Mm is present at the synaptic junction (original) (raw)

kDa protein, whose encoding cDNAs have been isolated CDC25Mm, a mouse Ras-Guanine nucleotide Ex-from mouse [10, 11], rat [12], and human [13, 14]. change Factor, is specifically expressed as a product of CDC25Mm presents a C terminal catalytic domain 140 kDa (p140) in the postnatal and adult brain. Immunothat acts in an in vitro system as a Ras-specific exhistochemical analysis indicates that it is present change factor [15, 16]. In addition the full-length prodthroughout the brain particularly concentrated in disuct contains two plextrin (PH) and one Dbl homology crete punctate structures. Subcellular fractionation of domain (DH) and a calmodulin binding IQ motif [17]. the mouse brain shows that p140 is present in synapto-While the role of Sos proteins in Ras activation has somes but not in highly purified synaptic vesicles. Morebeen deeply analyzed and is well understood, less is over, isolated postsynaptic densities (PSDs) are largely known on the signalling pathway(s) in which CDC25Mm/ enriched in CDC25Mm. This protein can be phosphory-Ras-GRF is involved. Recent evidence indicates that it is lated by calcium/calmodulin kinase II, the most abunnot coupled to tyrosine kinase receptors, but rather to dant protein in PSDs. Altogether these results suggest pathways involving trimeric G proteins [18, 19]. Morethat CDC25Mm is present at synaptic junctions and that over, through its calmodulin-binding IQ motif it appears it may be involved in synaptic signal transduction leadto mediate the calcium-induced Ras activation [17] and ing to Ras activation. ᭧ 1997 Academic Press the ensuing downstream cascade leading to transcriptional activation.