Localization of sulfonylurea receptor subunits, SUR2A and SUR2B, in rat heart.
To understand the possible functions and subcellular localizations of sulfonylurea receptors (SURs) in cardiac muscle, polyclonal anti-SUR2A and anti-SUR2B antisera were raised. Immunoblots revealed both SUR2A and SUR2B expression in mitochondrial fractions of rat heart and other cellular fractions such as microsomes and cell membranes. Immunostaining detected ubiquitous expression of both SUR2A and SUR2B in rat heart in the atria, ventricles, interatrial and interventricular septa, and smooth muscles and endothelia of the coronary arteries. Electron microscopy revealed SUR2A immunoreactivity in the cell membrane, endoplasmic reticulum (ER), and mitochondria. SUR2B immunoreactivity was mainly localized in the mitochondria as well as in the ER and cell membrane. Thus, SUR2A and SUR2B are not only the regulatory subunits of sarcolemmal K(ATP) channels but may also function as regulatory subunits in mitochondrial K(ATP) channels and play important roles in cardioprotection.
Zhou
Ming
M
Department of Anatomy, Akita University School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan. mzhou@med.akita-u.ac.jp
He
Hui-Jing
HJ
Suzuki
Ryoji
R
Liu
Ke-Xiang
KX
Tanaka
Osamu
O
Sekiguchi
Masaki
M
Itoh
Hideaki
H
Kawahara
Katsumasa
K
Abe
Hiroshi
H
D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D003331:Coronary Vessels / Q000378:metabolism; D007106:Immune Sera; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000648:ultrastructure; D009928:Organ Specificity; D015221:Potassium Channels / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D021122:Protein Subunits / Q000276:immunology / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011955:Receptors, Drug / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D064233:Sulfonylurea Receptors
D018528:ATP-Binding Cassette Transporters; D007106:Immune Sera; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D021122:Protein Subunits; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors