Question

To which of the following residues of the protein, the protein kinases do not add phosphate groups?

(a) serine

(b) cytosine

(c) threonine

(d) tyrosine

The question was asked by my school teacher while I was bunking the class.

The query is from Cell Signaling Systems topic in section Cell Signaling and Signal Transduction of Cell Biology

Answer 1

Right option is (b) cytosine

Easiest explanation: The protein kinases usually add phosphate groups to serine and threonine residues of their target proteins. A very important class of kinases also adds phosphate groups to the tyrosine residues.