MolPharm

Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text (PDF)
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by DE ROBERTIS, E.
Right arrow Articles by LA TORRE, J. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by DE ROBERTIS, E.
Right arrow Articles by LA TORRE, J. L.

Molecular Pharmacology, Vol 7, 97-103, Copyright © 1971 by the American Society for Pharmacology and Experimental Therapeutics

Multiple Binding Sites for Acetylcholine in a Proteolipid from Electric Tissue

E. DE ROBERTIS 1, GLENYS S. LUNT 1, and JOSÉ L. LA TORRE 1

1 Instituto de Anatomía General y Embriología, Facultad de Medicina, Universidad de Buenos Aires, Argentina

A special proteolipid protein fraction having a high affinity for binding to acetylcholine and other cholinergic drugs was isolated from electroplax of Electrophorus electricus. After extraction in chloroform-methanol (2:1 by volume) and column chromatography on Sephadex LH-20, the proteolipid appeared in a special peak together with the radioactive acetylcholine and increased in proportion with the amount of protein applied to the column. A saturation curve of this peak with respect to concentrations of 14C-acetylcholine between 7 x 10-7 and 5 x 10-5 M was constructed. The shape of this curve and the double-reciprocal plot of the data suggested the presence of more than one type of binding site. Assuming a homogeneous population of molecules having a molecular weight of 40,000, the use of the Scatchard equation suggested that there is a single high-affinity binding site with an apparent dissociation constant of 1 x 10-7 M and a group of low-affinity sites with a dissociation constant of 1 x 10-5 M. Since this proteolipid is present only in the electroplax membranes, these results are discussed in relation to the possible quantity of this material per electroplax or synaptic junction and its possible physiological significance as a receptor in cholinergic synapses.

Note:
ACKNOWLEDGMENTS The authors are indebted to Professor Gregorio Weber of the University of Illinois, to Dr. Enrique Rosengurt of the Instituto de Investigaciones Bioquímicas, and Dr. George G. Lunt for their helpful suggestions in the analysis of the data.

Submitted on June 9, 1970




This article has been cited by other articles:


Home page
 ScienceHome page
M. E. Eldefrawi, A. G. Britten, and A. T. Eldefrawi
Acetylcholine Binding to Torpedo Electroplax: Relationship to Acetylcholine Receptors
Science, July 23, 1971; 173(3994): 338 - 340.
[Abstract] [PDF]

Home page
 ScienceHome page
E. De Robertis
Molecular Biology of Synaptic Receptors
Science, March 12, 1971; 171(3975): 963 - 971.
[Abstract] [PDF]


Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
All ASPET Journals Molecular Pharmacology Pharmacological Reviews
Molecular Interventions Drug Metabolism and Disposition

Copyright © 1971 by the American Society for Pharmacology and Experimental Therapeutics