Proteodetergent

THE RELATIONSHIP BETWEEN CHOLINERGIC PROTEOLIPID AND PROTEODETERGENT IN TORPEDO ELECTROPLAX MEMBRANES... 

The fact that both the cholinergic proteodetergent (Olsen et al., 1972 Karlsson et al., 1972 Schmidt and Raftery, 1972 Klett et al., 1973 Eldefrawi and Eldefrawi, 1973) and the proteolipid (Barrantes 1973 Barrantes et al., 1975b) could be isolated and purified by affinity chromatography also favored the existence of similarities between these proteins. 

Fig. 2. Experiment in which Torpedo electroplax membranes were labeled with j Hj-MPTA and then submitted to extraction with 1% Triton X-100. The reextraction of the proteodetergent by chloroform-methanol(2 1) is also indicated (see the description in the text).

To investigate further the problem of the relationship between the cholinergic proteolipid and the proteodetergent, receptor-enr ched membranes from Torpedo electroplax were submitted to SDS polyacrylamide gel electrophoresis using the discontinuous buffer system of Laemmli (1970) as modified for slab gels by Studier (1973). 

IV. Transfer of Proteolipid into Proteodetergent. Methods were developed to transfer the cholinergic proteolipid into a water solution by the addition of detergents and the binding of a-bungaro toxin to the proteolipid in aqueous media could be demonstrated (Fig. 1). 

VI. Extraction of the 39 000 subunit. The results of the SDS polyacrylamide gel electrophoresis suggest that the subunit of 39,000, which carries the binding site, is extracted by the organic solvent (Fig. 3). Since the cholinergic proteodetergent has a much larger molecular weight, with four different subunits (Karlin 1974), we may conclude that the proteolipid probably represents only a... 

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