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Biochemical characteristics of free and junctional sarcoplasmic reticulum and of transverse tubules in human skeletal muscle
Author(s) -
Damiani Ernesto,
Barillari Alfredo,
Tobaldin Gianantonio,
Pierobon Sandra,
Margreth Alfredo
Publication year - 1989
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880120411
Subject(s) - endoplasmic reticulum , skeletal muscle , anatomy , chemistry , medicine , biology , microbiology and biotechnology
The microsomal fraction of normal human skeletal muscle was subfractionated by isopycnic sucrose‐density centrifugation, using the procedure originally described by Saito et al. 38 for rabbit fast muscle, and specific markers of the junctional face membrane of terminal cisternae (TC) (ryanodine receptor, high‐molecular‐weight feet proteins and membrane‐associated calcium‐binding protein calsequestrin), of the sarcoplasmic reticulum (SR) Ca‐pump membrane (chicken antibody to rabbit Ca‐ATPase), and of transverse tubules (TT) (dihydropiridine receptor, membrane cholesterol), respectively. The results show that isolated TC from human skeletal muscle share extensive morphological characteristics, protein composition, as well as Ca‐release properties with rabbit TC, as tested with an inhibitor (Ruthenium red) and an activator (doxorubicin) of SR Ca‐release. The Ca‐pump membrane of human muscle SR, in distinction to rabbit fast muscle SR, showed a relatively low specific activity of the Ca‐ATPase, as expected from the mixed fiber composition of human muscles, but shared the presence of minor protein components, such as a Con A binding protein of about 57 kDa and blue‐staining peptides in the 170–120 kDa range of molecular weights. Human muscle TT, as isolated from the same sucrose gradient, demonstrated a high affinity (3H)‐dihydropiridine binding activity in the range of previously reported values for purified TT from rabbit skeletal muscle.