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Functional association between nicotinic acetylcholine receptor and sarcomeric proteins via actin and desmin filaments
Author(s) -
Mitsui Takao,
Kawajiri Masakazu,
Kunishige Makoto,
Endo Takenori,
Akaike Masashi,
Aki Kenji,
Matsumoto Toshio
Publication year - 2000
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/(sici)1097-4644(20000615)77:4<584::aid-jcb6>3.0.co;2-u
Subject(s) - desmin , dystrophin , utrophin , actin , digitonin , acetylcholine receptor , chemistry , myosin , microbiology and biotechnology , calponin , actin binding protein , nicotinic acetylcholine receptor , skeletal muscle , biology , biochemistry , cytoskeleton , receptor , actin cytoskeleton , anatomy , vimentin , immunohistochemistry , cell , immunology , enzyme
By affinity chromatography utilizing α‐cobrotoxin from digitonin‐solubilized fractions of rabbit skeletal muscle, we found that many proteins are associated with the nicotinic acetylcholine receptor (AChR). In addition to the proteins we previously reported to bind to AChR (including dystrophin‐dystrophin‐associated protein (DAP) complex, utrophin, rapsyn, and actin; Mitsui et al. [1996] Biochem. Biophys. Res. Commun.224:802–807), α‐actinin, desmin, myosin, tropomyosin, troponin T, and titin are also identified to be associated with AChR. Alkaline treatment or Triton X‐100 solubilization released dystrophin‐DAP complex, utrophin, and rapsyn from the AChR fraction, while actin and desmin remained associated. These findings demonstrate that AChR is supported primarily by a submembranous organization of actin and desmin filaments, and is linked to sarcomeric proteins via these filaments. To further investigate whether the association has any functional role, we studied the effect of acetylcoline on ATPase activity of the AChR fraction. Acetylcholine (0.5–4 μM) significantly activated Mg 2+ ‐ATPase activity of digitonin‐solubilized AChR fraction ( P < 0.05). Furthermore, we found that desmin as well as actin activated myosin Mg 2+ ‐ATPase activity. From these findings, it is suggested that desmin and actin form a submembranous organization in the postsynaptic region, and function as mediators of excitation of AChR to the sarcomeric contraction system. J. Cell. Biochem. 77:584–595, 2000. © 2000 Wiley‐Liss, Inc.