Junker J, Sommer J R, Sar M, Meissner G
School of Pharmacy, Campbell University, Buies Creek, North Carolina 27506.
J Biol Chem. 1994 Jan 21;269(3):1627-34.
The ryanodine receptor (RYR)/Ca2+ release channel of avian cardiac muscle was localized by immunocytochemical techniques and biochemically characterized using isolated membrane and receptor protein fractions. Monoclonal antibody C3-33 raised against the canine cardiac RYR bound to the junctional sarcoplasmic reticulum of pigeon and finch hearts, both at peripheral couplings and at extended junctional sarcoplasmic reticulum (EJSR). Immunoblots of sarcoplasmic reticulum vesicles from pigeon and finch hearts showed this antibody recognized a single high molecular weight protein, which co-migrated with the canine M(r) 565,000 RYR/Ca2+ release channel polypeptide. The pigeon heart RYR bound [3H]ryanodine with high affinity in a Ca(2+)-dependent manner, comparable to the canine cardiac RYR. Purification of the pigeon RYR yielded a 30 S protein complex, which bound the maximum calculated amount of [3H]ryanodine ((440 +/- 60) pmol/mg protein), assuming one high affinity site/tetrameric 30 S RYR comprised of M(r) 565,000 polypeptides. Autoradiography of isolated finch cardiac myocytes indicated [3H]ryanodine binding throughout the cells. These results suggest that avian heart contains a single population of RYRs, and thereby support the hypothesis that avian EJSR contains functional calcium release channels which, because of the absence of transverse tubules, can be located micrometers away from the surface membrane in avian heart.
利用免疫细胞化学技术对禽心肌的兰尼碱受体（RYR）/Ca²⁺释放通道进行了定位，并使用分离的膜和受体蛋白组分对其进行了生化特性分析。针对犬心肌RYR产生的单克隆抗体C3 - 33与鸽和雀心脏的连接肌浆网结合，在外周偶联处和扩展连接肌浆网（EJSR）均有结合。鸽和雀心脏肌浆网囊泡的免疫印迹显示，该抗体识别一种单一的高分子量蛋白，其与犬M（r）565,000的RYR/Ca²⁺释放通道多肽共迁移。鸽心脏RYR以Ca²⁺依赖的方式与[³H]兰尼碱高亲和力结合，与犬心肌RYR相当。鸽RYR的纯化产生了一个30 S蛋白复合物，假设由M（r）565,000多肽组成的四聚体30 S RYR有一个高亲和力位点，则该复合物结合了最大计算量的[³H]兰尼碱（（440±60）pmol/mg蛋白）。分离的雀心肌细胞的放射自显影表明[³H]兰尼碱在整个细胞中结合。这些结果表明禽心脏含有单一群体的RYR，从而支持了这样的假说：禽EJSR含有功能性钙释放通道，由于缺乏横管，这些通道在禽心脏中可位于距表面膜数微米远的位置。
