Chromosomal mapping of a family of human glutamine synthetase genes: functional gene (GLUL) on 1q25, pseudogene (GLULP) on 9p13, and three related genes (GLULL1, GLULL2, GLULL3) on 5q33, 11p15, and 11q24.

Glutamine synthetase (GS) is a ubiquitous enzyme that catalyzes the ATP-dependent conversion of glutamate to glutamine using ammonia as the nitrogen source. Using human GS cDNA as a probe, a bacterial artificial chromosome (BAC) library consisting of two-fold coverage of the human genome was screened, and 18 clones were obtained. The restriction analysis of the human insert DNAs provided a basis to divide these 18 BAC clones into five groups, suggesting the existence of a GS gene family in the human genome. PCR analysis using three sets of primers designed from the reported sequences for GS cDNA and a processed pseudogene identified the corresponding BAC clones. Fluorescence in situ hybridization analysis revealed the chromosomal localization of these five genes: the GS gene to 1q25 (GLUL), the processed pseudogene to 9p13 (GLULP), and three related gene to 5q33 (GLULL1), 11p15 (GLULL2), and 11q24 (GLULL3), respectively.