Question

The synthesis of 5-phosphoribosylamine from PRPP is

I. inhibited allosterically by ATP and GTP.
II. activated by PRPP via feed forward activation.
III. controlled by cAMP dependent phosphorylation.

A: I, II, III,
B: I, II
C: II, III
D: II only
E: III only

Answer 1

The correct answer is option B: "I, II".

Step-by-step explanation:

The synthesis of 5-phosphoribosylamine from phosphoribosyl pyrophosphate (PRPP) is inhibited allosterically by ATP and GTP and activated by PRPP via feed forward activation. The enzyme that regulate this process is the enzyme amidophosphoribosyltransferase (AMPRT), which is stimulated by increased PRPP concentrations and is inhibited allosterically by ATP and GTP as well as IMP, AMP, and GMP.