The chloroplast genome in land plants encodes 4 rRNAs, 30 tRNAs, and 60 proteins.

TLS Online TPP Program

#Id: 8608

#Unit 2. Cellular Organization

There are three D cyclins in mammals:

cyclins D1, D2, and D3

TLS Online TPP Program

#Id: 8609

#Unit 2. Cellular Organization

In free CDK2, the A-loop blocks access of protein substrates to the γ phosphate of the bound ATP.

TLS Online TPP Program

#Id: 8610

#Unit 2. Cellular Organization

TLS Online TPP Program

#Id: 8611

#Unit 2. Cellular Organization

Nonphosphorylated CDK bound to one of its cyclin partners has minimal but detectable protein kinase activity in vitro, although it may be essentially inactive in vivo.

TLS Online TPP Program

#Id: 8612

#Unit 2. Cellular Organization

Phosphorylation of a critical threonine residue in the activation loop, Thr-160, allowing substrates to access the active site of the CDK

TLS Online TPP Program

#Id: 8613

#Unit 2. Cellular Organization

Threonine -160 phosphorylation is mediated by 

CDK-activating kinase (CAK)