1) A group of enzymes that catalyzes the phosphorylation of serine or threonine residues in proteins, with ATP or other nucleotides as phosphate donors.

2) group of enzymes that catalyze the phosphorylation of serine or threonine residues in proteins, with ATP or other nucleotides as phosphate donors.

3) A group of enzymes that catalyzes the phosphorylation of serine or threonine residues in proteins, with ATP or other nucleotides as phosphate donors.