Premium
Photoaffinity labelling of the phenylalkylamine receptor of the skeletal muscle transverse‐tubule calcium channel
Author(s) -
Striessnig Jörg,
Knaus Hans-Günther,
Grabner Manfred,
Moosburger Kurt,
Seitz Werner,
Lietz Helmut,
Glossmann Hartmut
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)81354-6
Subject(s) - photoaffinity labeling , chemistry , calcium , calcium channel , membrane , biochemistry , receptor , skeletal muscle , biophysics , biology , endocrinology , organic chemistry
The tritiated arylazido phenylalkylamine (‐)‐5‐[(3‐azidophenethyl)[ N ‐ methyl ‐ 3 H]methylamino]‐2‐(3,4,5‐tri‐methoxyphenyl)‐2‐isopropylvaleronitrile was synthesized and used to photoaffinity label the phenylalkylamine receptor of the membrane‐bound and purified calcium channel from guinea‐pig skeletal muscle trans‐verse‐tubule membranes. The photoaffinity ligand binds reversibly to partially purified membranes with a K d of 2.0 ± 0.5 nM and a B max of 17.0 ± 0.9protein. Binding is stereospecifically regulated by all three classes of organic calcium channel drugs. A 155 kDa band was specifically photolabelled in transverse‐tubule particulate and purified calcium channel preparations after ultraviolet irradiation. Additional minor labelled polypeptides (92, 60 and 33 kDa) were only observed in membranes. The heterogeneous 155 kDa region of the purified channel was resolved into two distinct silver‐stained polypeptides after reduction (i.e. 155 and 135 kDa). Only the 155 kDa polypeptide carries the photoaffinity label and it is concluded that the 135 kDa polypeptide (which migrates as a 165 kDa band under alkylating conditions) is not a high‐affinity drug receptor carrying subunit of the skeletal muscle transverse‐tubule L‐type calcium channel.