Figure 2. (A) Alignment of amino acid sequences surrounding the T-loop region of CDK1 from worm, fly, and mouse, showing the positions of conserved amino acid sequence mutated in the hypomorphic alleles of cdk-1 (ne2257 [I173F] and ne236 [R176H]) isolated in genetic screens using C.elegans, boxed in red or yellow, respectively. Invariant amino acids are indicated with an asterisk. (B) Crystal structure of activated mouse CDK2/CyclinA complex. Amino acids corresponding to those affected in the hypomorphic alleles of cdk-1, Ile173 in the case of ne2257, and Arg176 in the case of ne236 are shown in red and yellow, respectively. The amino acids corresponding to those affected in 2 cyb-3 suppressor alleles of cdk-1(ne2257) are also shown in magenta (ne4276) and light blue (ne4277).