Glutamate 5-kinase <p> L-glutamate 5-phosphotransferase, (gamma-glutamyl kinase, proB, <db_xref db="EC" dbkey="2.7.2.11"/>), catalyzes the first step in proline biosynthesis<reaction> ATP + L-glutamate = ADP + L-glutamate 5-phosphate.</reaction>the product of which rapidly cyclizes to 5-oxoproline and phosphate.</p>