If src gene present in virus a. A kinase is an enzyme that puts phosphate groups on other molecules. In other words, it phosphorylates other molecules. A tyrosine kinase puts phosphate on the amino acid tyrosine. Only amino acids with an OH group can get phosphorylated.
Tyrosine has an OH and so do serine and threonine.
We know shoehow phosphorylating tyrosine is important. We don't know the molecular details and all the steps of what happens because too many different things are getting phosphorylated. The src gene originally came from a cell. When an RNA virus enters a cell, it makes a DNA copy of itself using the enzyme encoded by the pol gene. The excision is not precise, so part of the host DNA gets taken along.