Fig. 1.

Glutamine synthetase (GS) protein and mRNA expression in different regions of the mouse kidney. A: GS protein expression by immunoblot analysis. A 45-kDa product was present in samples from the outer cortex, outer stripe of the outer medulla (OMo), and inner stripe of the outer medulla (OMi). B: results of RT-PCR amplification of mRNA obtained from the cortex and OMi. Amplification of a 258-bp product consistent with GS mRNA expression was observed using samples from the cortex and OMi when reverse transcriptase was performed (+rt) but not in the absence of reverse transcriptase (−rt). Thus, GS mRNA and protein are widely expressed in the mouse kidney and are present in sites in which proximal tubule cells are not present, specifically the OMi.