Which statement(s) about protein phosphorylation is/are true?
a) Membrane receptors that receive signals, come together to form a dimer and become activated through tyrosine phosphorylation are called tyrosine-kinases.
b) Phosphorylation by a kinase brings a conformational change to a protein which acts as a fast on-off switch.
c) Cannot occur in yeast because they lack protein phosphatases.
d) Requires binding of a hormone to a receptor in the cytosol.

Ode to coffee! Caffeine inhibits phosphodiesterase. So since Brisch drinks buckets of "jet fuel" coffee, what would increase in her cells?
a) phosphorylated proteins
b) G proteins
c) cAMP
d) a) and c)