Identification of frog photoreceptor plasma and disk membrane proteins by radioiodination
Several functions have been identified for the plasma membrane of the rod outer segment, including control of light-dependent changes in sodium conductance and a sodium-calcium exchange mechanism. However, little is known about its constituent proteins. Intact rod outer segments substantially free of contaminants were prepared in the dark and purified on a density gradient of Percoll. Surface proteins were then labeled by lactoperoxidase-catalyzed radioiodination, and intact rod outer segments were reisolated. Membrane proteins were identified by polyacrylamide gel electrophoresis and autoradiography. The surface proteins labeled included rhodopsin, the major membrane protein, and 12 other proteins. To compare the protein composition of plasma membrane with that of the internal disk membrane, purified rod outer segments were lysed by hypotonic disruption or freeze-thawing, and plasma plus disk membranes were radioiodinated. In these membrane preparations, rhodopsin was the major iodinated constituent, with 12 other proteins also labeled. Autoradiographic evidence indicated some differences in protein composition between disk and plasma membranes. A quantitative comparison of the two samples showed that labeling of two proteins, 24 kilodaltons (kDa) and 13 kDa, was enriched in the plasma membrane, while labeling of a 220-kDa protein was enriched in the disk membrane. These plasma membrane proteins may be associated with important functions such as the light-sensitive conductance and the sodium-calcium exchanger.
- Research Organization:
- Univ. of Wisconsin, Madison
- OSTI ID:
- 6470450
- Journal Information:
- Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:6; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Affinity labeling of the galactose/N-acetylgalactosamine-specific receptor of rat hepatocytes: preferential labeling of one of the subunits
Identification of the sodium-calcium exchanger as the major ricin-binding glycoprotein of bovine rod outer segments and its localization to the plasma membrane
Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ATP
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CELL CONSTITUENTS
CELL MEMBRANES
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELECTROPHORESIS
HALIDES
HALOGEN COMPOUNDS
HALOGENATION
INORGANIC PHOSPHORS
INTERMEDIATE MASS NUCLEI
IODIDES
IODINATION
IODINE 125
IODINE COMPOUNDS
IODINE ISOTOPES
ISOTOPES
LABELLING
LIGHT NUCLEI
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
MEMBRANES
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PHOSPHORS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOTOSENSITIVITY
PIGMENTS
PROTEINS
RADIOISOTOPES
RECEPTORS
RHODOPSIN
SENSITIVITY
SODIUM COMPOUNDS
SODIUM IODIDES