Characterization and comparison of the NR3A subunit of the NMDA receptor in recombinant systems and primary cortical neurons.
Recently, we cloned and began to characterize a new N-methyl-D-aspartate receptor (NMDAR) subunit, NR3A. Here we extend our earlier findings by showing that recombinantly expressed NR3A in COS cells is biochemically associated with both NR1 and NR2 subunits. In the oocyte or HEK 293 cell expression systems, co-injection of NR3A with NR1/NR2 subunits acts in a dominant-interfering manner, resulting in a decrease in NMDAR unitary conductance, decrease in Ca(2+) permeability, decrease in Mg(2+) sensitivity, and slight increase in mean open time compared with NR1/NR2 channels. The smaller unitary conductance channel has also been observed in primary cortical neurons cultured from wild-type rodent on postnatal day 8 (P8) and similarly found to be relatively insensitive to Mg(2+) block. Consistent with these findings, whole cell NMDA-evoked currents are larger in NR3A-deficient mice compared with wild-type mice, and this effect follows a developmental pattern similar to that of NR3A protein expression on Western blots, with peak expression at P8. Finally, a new longer splice variant of NR3A has been cloned and found to be expressed in rodent cortical neurons by single-cell RT-PCR and in situ hybridization.
Sasaki
Yasnory F
YF
Center for Neuroscience and Aging, The Burnham Institute, La Jolla, California 92037, USA.
Rothe
Thomas
T
Premkumar
Louis S
LS
Das
Saumya
S
Cui
Jiankun
J
Talantova
Maria V
MV
Wong
Hon-Kit
HK
Gong
Xiandi
X
Chan
Shing Fai
SF
Zhang
Dongxian
D
Nakanishi
Nobuki
N
Sucher
Nikolaus J
NJ
Lipton
Stuart A
SA
D017398:Alternative Splicing; D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism*; D004553:Electric Conductivity; D005260:Female; D015151:Immunoblotting; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology; D008274:Magnesium / Q000494:pharmacology; D051379:Mice; D009474:Neurons / Q000378:metabolism*; D009865:Oocytes; D010539:Permeability; D011233:Precipitin Tests; D021122:Protein Subunits; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014982:Xenopus laevis
D007473:Ion Channels; D021122:Protein Subunits; D012333:RNA, Messenger; D016194:Receptors, N-Methyl-D-Aspartate; D011994:Recombinant Proteins; D008274:Magnesium; D002118:Calcium