APRTase catalyzes the following reaction in the purine nucleotide salvage pathway:
Adenine + Phosphoribosyl Pyrophosphate (PRPP) → Adenylate (AMP) + Pyrophosphate (PPi)
In organisms that can synthesize purines de novo, the nucleotide salvage pathway provides an alternative that is  energetically more efficient.
It can salvage adenine from the polyamine biosynthetic pathway or from dietary sources of purines.
Although APRTase is functionally redundant in these organisms, it becomes more important during periods of rapid growth, such as embryogenesis and tumor growth.
It is constitutively expressed in all mammalian tissue.

In protozoan parasites, the nucleotide salvage pathway provides the sole means for nucleotide synthesis.
Since the consequences of APRTase deficiency in humans is comparatively mild and treatable, it may be possible to treat certain parasitic infections by targeting APRTase function.

In plants, as in other organisms, ARPTase functions primarily for the synthesis of adenylate.
It has the unique ability to metabolize cytokinins—a plant hormone that can exist as a base, nucleotide, or nucleoside—into adenylate nucleotides.

APRT is functionally related to hypoxanthine-guanine phosphoribosyltransferase (HPRT).
APRTase catalyzes the following reaction in the purine nucleotide salvage pathway:
Adenine + Phosphoribosyl Pyrophosphate (PRPP) → Adenylate (AMP) + Pyrophosphate (PPi)
In organisms that can synthesize purines de novo, the nucleotide salvage pathway provides an alternative that is  energetically more efficient. It can salvage adenine from the polyamine biosynthetic pathway or from dietary sources of purines. Although APRTase is functionally redundant in these organisms, it becomes more important during periods of rapid growth, such as embryogenesis and tumor growth. It is constitutively expressed in all mammalian tissue.
In protozoan parasites, the nucleotide salvage pathway provides the sole means for nucleotide synthesis. Since the consequences of APRTase deficiency in humans is comparatively mild and treatable, it may be possible to treat certain parasitic infections by targeting APRTase function.
In plants, as in other organisms, ARPTase functions primarily for the synthesis of adenylate. It has the unique ability to metabolize cytokinins—a plant hormone that can exist as a base, nucleotide, or nucleoside—into adenylate nucleotides.
APRT is functionally related to hypoxanthine-guanine phosphoribosyltransferase (HPRT).
Adenine phosphoribosyltransferase