Project Summary/Abstract A unique level of metabolic enzyme organization within a cell is the formation of metabolons. Metabolons have been hypothesized to promote more efficient processing of metabolites through enzyme clustering to meet cellular demand. In the case of high purine demand, the enzymes involved in de novo purine biosynthesis spatially organize to form multi-enzyme clusters coined as purinosomes. Conditions that impact purine biosynthesis were shown to modulate purinosome formation suggesting that the purinosome may act as a marker for de novo purine biosynthetic pathway activation. This proposal focuses on exploring the purinosome as an example of a transient metabolon. These molecular understandings generated will provide further insights into how the cell leverages the de novo purine biosynthetic pathway under high purine demand and provides a general framework for studying metabolons.