Formation of molecular complexes by N-methyl-D-aspartate receptor subunit NR2B and ryanodine receptor 2 in neonatal rat myocard.
The N-methyl-d-aspartate (NMDA) receptor is a glutamate gated cation channel prevalent in the postsynaptic membranes of central nervous system neurons. The neurotransmitter receptor complex is thought to represent a tetramer where variable NR2 or NR3 polypeptides form heteromeric assemblies with an obligatory NR1 subunit. Recently, we showed that cardiac myocytes from perinatal rats transiently express the NMDA receptor subunit NR2B, the function of which in heart is unknown. To characterize the cardiac NR2B protein, we determined its subcellular distribution and specific molecular interaction partners. By immunostaining of rat heart tissue slices and acutely dissociated cardiac myocytes, the NR2B antigen was localized at the sarcomeric Z-bands. Using immunoprecipitation of detergent-solubilized NR2B protein and subsequent analysis employing matrix-assisted laser desorption/ionization time of flight mass spectrometry, ryanodine receptor 2 was identified as a molecular interaction partner of the cardiac NR2B polypeptide. Differences in antibody recognition indicate that the cardiac NR2B polypeptide carries a structurally altered C terminus as compared with the NR2B variant prevalent in central nervous system. Based on its localization and protein interaction, the function of cardiac NR2B protein may relate to mechanosensitivity or play a role in the regulation of the contractile apparatus of neonatal heart.
Seeber
Silke
S
Institut für Biochemie, Emil-Fischer-Zentrum, Friedrich-Alexander-Universität Erlangen-Nürnberg, Fahrstrasse 17, D-91054 Erlangen, Germany.
Humeny
Andreas
A
Herkert
Matthias
M
Rau
Thomas
T
Eschenhagen
Thomas
T
Becker
Cord-Michael
CM
D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D002478:Cells, Cultured; D002490:Central Nervous System / Q000378:metabolism; D017931:DNA Primers; D066298:In Vitro Techniques; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D017931:DNA Primers; C121001:NR2B NMDA receptor; D010446:Peptide Fragments; D021122:Protein Subunits; D016194:Receptors, N-Methyl-D-Aspartate; D011994:Recombinant Proteins; D019837:Ryanodine Receptor Calcium Release Channel