Title : Rap1A antagonizes the ability of Ras and Ras-Gap to inhibit muscarinic K+ channels.

Pub. Date : 1991 Nov 25

PMID : 1939245






5 Functional Relationships(s)
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1 Rap1A is a Ras-related GTP binding protein which has an amino acid sequence identical to that of Ras in the putative "effector" domain (amino acids 32-40). Guanosine Triphosphate RAP1A, member of RAS oncogene family Homo sapiens
2 We observed that both Rap1A-GDP and Rap1A-guanosine 5"-3-O-(thio)triphosphate (GTP gamma S) were able to block the inhibitory effect of Ras-GAP upon channel activation. Guanosine Triphosphate RAP1A, member of RAS oncogene family Homo sapiens
3 We observed that both Rap1A-GDP and Rap1A-guanosine 5"-3-O-(thio)triphosphate (GTP gamma S) were able to block the inhibitory effect of Ras-GAP upon channel activation. Guanosine Triphosphate RAP1A, member of RAS oncogene family Homo sapiens
4 A Rap1A Thr35----Ala mutation which bound GTP gamma S did not prevent K+ channel inhibition by Ras-GAP, suggesting that the antagonism by wild type Rap1A involves an interaction with GAP in the effector domain. Guanosine Triphosphate RAP1A, member of RAS oncogene family Homo sapiens
5 The effectiveness of Rap1A to inhibit Ras-GAP is dependent upon the amount of Ras-GAP present in the assay and can also be overcome by the addition of GTP-bound N-Ras (GC-43), suggesting a competitive mechanism is operative. Guanosine Triphosphate RAP1A, member of RAS oncogene family Homo sapiens