Horgan D J, Kuypers R
Arch Biochem Biophys. 1987 Mar;253(2):377-87. doi: 10.1016/0003-9861(87)90191-3.
A new method for the preparation of transverse tubules (T-tubules) from rabbit skeletal muscles is reported. When crude sarcoplasmic reticulum (SR) preparations were centrifuged on sucrose density gradients containing buffering ions (buffered gradients) 70-80% of the material sedimented as a single heavy band in the region of 43% sucrose. When this fraction (or crude SR) was recentrifuged on sucrose gradients prepared free of buffer or other ions (ion-free gradients) the heavy band dissociated into three fractions of different densities. The lightest fraction sedimented at 28% sucrose and was identified as T-tubules on the basis of its nitrendipine and ouabain binding properties. The enzymatic properties, cholesterol contents, and protein compositions of the fractions obtained when SR is centrifuged on buffered and ion-free sucrose density gradients were measured. The T-tubules were enriched in cholesterol and in marker enzymes for surface membranes while the other fractions were shown to be terminal cisternae and longitudinal cisternae on the basis of their (Ca2+,Mg2+)-ATPase activities and characteristic protein profiles.
本文报道了一种从兔骨骼肌制备横小管（T小管）的新方法。当粗制肌浆网（SR）制剂在含有缓冲离子的蔗糖密度梯度（缓冲梯度）上离心时，70 - 80%的物质在43%蔗糖区域以单一重带形式沉淀。当该部分（或粗制SR）在不含缓冲液或其他离子的蔗糖梯度（无离子梯度）上再次离心时，重带解离为三个不同密度的部分。最轻的部分在28%蔗糖处沉淀，根据其尼群地平和哇巴因结合特性被鉴定为T小管。测定了SR在缓冲和无离子蔗糖密度梯度上离心时获得的各部分的酶学性质、胆固醇含量和蛋白质组成。T小管富含胆固醇和表面膜标记酶，而其他部分根据其（Ca2 +，Mg2 +）-ATP酶活性和特征性蛋白质谱显示为终池和纵池。
