A novel yeast protein showing specific association with the cyclin-dependent kinase 5.

The present study describes a significant amino acid sequence homology between neuronal Cdk5 activator (nck5a) and an open reading frame of an unknown gene on the yeast S. cerevisiae chromosome III. A cDNA encoding a 25 kDa fragment of this yeast protein, the region containing homologous sequence to nck5a was cloned and expressed in E. coli as a glutathine-S-transferase fusion protein (GST-p25Y). GST-p25Y was found to block the in vitro activation of Cdk5 by nck5a and to affinity precipitate Cdk5 from bovine brain extract. The observations indicate that the yeast protein is capable of specific and high affinity association with Cdk5.