Structure-function relationship of the small GTPase rab5.

摘要: Overexpression of rab5 via a Sindbis virus vector resulted in 2-3-fold stimulation horseradish peroxidase uptake BHK-21 cells. Based on this functional assay activity, we conducted extensive mutational analysis the structure-function relationship rab5. A total 21 deletion and substitution mutations were created their effects activity examined. Deletion entire C-terminal tetrapeptide motif CCSN abolished activity. mutant with last three residues deleted, however, showed residual Truncation only two from C terminus had no effect biological containing 4-residue N retained full comparison wild-type N-terminal 19 partially blocked Substitution guanine nucleotide binding motifs dramatic function. In addition to previously reported N133I mutation, S34N mutation also defective form that was dominant inhibitor endogenous The Q79L (the ras equivalent Q61L decreases intrinsic GTPase-activating protein-stimulated GTPase activities), S35N which is immediately downstream first GTP/GDP motif, decreased by approximately 4-fold inactivated Mutations several other conserved (K22A, F57Y, R81A) partial loss Eight around putative effector domain little light these data, discussed compared ras, prototype small GTPases.