Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Characterization of the Junctional Face Membrane from Terminal Cisternae of Sarcoplasmic Reticulum

Brian Costello, Christopher Chadwick, Akitsugu Saito, Alice Chu, Andreas Maurer and Sidney Fleischer
The Journal of Cell Biology
Vol. 103, No. 3 (Sep., 1986), pp. 741-753
Stable URL: http://www.jstor.org/stable/1611996
Page Count: 13
  • More info
  • Cite this Item
Characterization of the Junctional Face Membrane from Terminal Cisternae of Sarcoplasmic Reticulum
Preview not available

Abstract

We have recently described a preparation of junctional terminal cisternae (JTC) from fast skeletal muscle of rabbit hind leg. The fraction differs from other heavy sarcoplasmic reticulum (SR) fractions in that it contains a substantial amount of junctional face membrane (JFM) (15-20% of the membrane) with morphologically well-defined junctional feet structures. In common with other heavy SR preparations, it contains predominantly the calcium pump membrane (80-85% of the membrane) and compartmental contents (CC), consisting mainly of calcium-binding protein (calsequestrin). In this study, a modified procedure for the preparation of JTC from frozen rabbit back muscle is described. The yield is substantially greater (threefold per weight of muscle), yet retaining characteristics similar to JTC from fresh hind leg muscles. Methodology has been developed for the disassembly of the JTC. This is achieved by selectively extracting the calcium pump membrane with 0.5% Triton X-100 in the presence of 1 mM CaCl2 to yield a complex of JFM with CC. The CC are then solubilized in the presence of EDTA to yield JFM. This fraction contains unidirectionally aligned junctional feet structures protruding from the cytoplasmic face of the membrane with repeat spacings comparable to that observed in JTC. The JFM contains 0.16 μmol phosphorus (lipid) per milligram protein. Characteristic proteins include 340 and 79-kD bands, a doublet at 28 kD, and a component that migrates somewhat slower than or equivalent to the calcium pump protein. Approximately 10% of the calcium-binding protein remains bound to the JFM after EDTA extraction, indicating the presence of a specific binding component in the JFM. The JFM, which is involved in junctional association with transverse tubule and likely in the Ca2+ release process in excitation-contraction coupling, is now available in the test tube.

Page Thumbnails

  • Thumbnail: Page 
741
    741
  • Thumbnail: Page 
742
    742
  • Thumbnail: Page 
743
    743
  • Thumbnail: Page 
744
    744
  • Thumbnail: Page 
745
    745
  • Thumbnail: Page 
746
    746
  • Thumbnail: Page 
747
    747
  • Thumbnail: Page 
748
    748
  • Thumbnail: Page 
749
    749
  • Thumbnail: Page 
750
    750
  • Thumbnail: Page 
751
    751
  • Thumbnail: Page 
752
    752
  • Thumbnail: Page 
753
    753