Site-directed mutagenesis of Tyr-15 to Phe in cdc2:
A)results in the wee phenotype.
B)results in a phenotype similar to that caused by mutation in cdc25.
C)increases the possible number of phosphate groups on Cdc2.
D)prevents binding of Cdc13.

Question

Quizplus · Accepted Answer

The substitution of tyrosine with phenylalanine at position 15 in cdc2 confers a wee phenotype, characterized by early entry into mitosis, shortened G2 phase, and small cell size. This mutation prevents tyrosine dephosphorylation of cdc2, which is necessary for its activation by cyclin-dependent kinase-activating kinase (CAK). Therefore, cdc2 remains active throughout the cell cycle, driving cells into mitosis prematurely. This phenotype is similar to that caused by mutations in cdc25, a phosphatase that dephosphorylates cdc2 on tyrosine 15.

Site-Directed Mutagenesis of Tyr-15 to Phe in Cdc2