How might a protein kinase select the correct residues
tophosphorylate given the availability of serine and
threonineresidues on the surface of globular proteins?

The flanking residues  facilitate recognition and specificity.

Explanation:

The kinase is able to to specifically phosphorylate serine and threonine due to the recognition of the flanking residues. Altogether, these form a consensus sequence across the substrate.

i don't know. the other person does though.

answer: i say it foxes

explanation:

you need to give us the answer options to for me to offical decide.