Molecular Properties of the cGMP-gated Cation Channel of Rod Photoreceptor Cells as Probed with Monoclonal Antibodies
Monoclonal antibodies have been generated against different epitopes of the cGMP-gated channel of bovine rod outer segments for use as probes to study the molecular properties of this channel protein. These monoclonal antibodies selectively labeled a 63 kDa polypeptide in both bovine rod outer segment membranes and purified channel preparations and crossreact with a 63 kDa polypeptide in rod outer segment preparations from other mammalian retinas. Immunoprecipitation studies have confirmed the identity of the 63 kDa protein as the cGMP-gated channel of rod outer segment membranes and have shown that the channel is associated with a 240 kDa protein. Solid phase radioimmune competition studies on isolated rod outer segment disks and plasma membranes have indicated that the plasma membrane has a channel density which is over 200 times greater than that in disk membranes. A monoclonal antibody against a synthetic peptide also been developed and used to study the properties of the N-terminal segment of the channel.
KeywordsUnbind Fraction Sepharose Column Disk Membrane Immobilon Membrane Channel Polypeptide
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