REGIONAL, DEVELOPMENTAL AND INTERSPECIES EXPRESSION OF THE 4 NMDAR2 SUBUNITS, EXAMINED USING MONOCLONAL-ANTIBODIES

Mouse monoclonal antibodies were raised against bacterially expressed protein sequences of the NR2A, NR2B, NR2C and NR2D subunits of the rat NMDA receptor. From immunoblots of rat brain proteins, the apparent m olecular weights of these subunits were 165, 170, 135 and 145 kDa, res pectively. Proteins of similar masses were observed on immunoblots of specifically transfected HEK293 cells. Deglycosylation with endoglycos idase F reduced the mass of each endogenous NR2 subunit by approximate to 10 kDa. In distribution studies, NR2A-immunoreactive protein (IRP) was located throughout the adult rat brain, NR2B-IRP was primarily in the forebrain, NR2C-IRP was predominantly in the cerebellum and NR2D- IRP was mainly found in the thalamus, midbrain and brainstem. Whereas NR2A- and NR2C-IRPs increased during rat brain post-natal development, NR2B- and NR2D-IRPs were abundant at birth and declined with age, esp ecially in cerebellum. NR2-IRPs of mouse, rabbit, frog and human brain were of sizes similar to those of the corresponding rat subunits and were similarly distributed. In summary, NR2 subunits are large glycopr oteins whose specific expression profiles in the brain are development ally and regionally regulated and which are similarly expressed in a v ariety of species. (C) 1997 Elsevier Science B.V.