Identification of the 5-hydroxytryptamine2C receptor as a 60-kDa N-glycosylated protein in choroid plexus and hippocampus.
The rat 5-hydroxytryptamine2C (5-HT2C) receptor was identified as N-glycosylated polypeptide of 60-kDa apparent molecular mass using antibodies against its putative third and fourth (C-terminal) cytoplasmic domain. To show that the polypeptides detected on western blots and by immunoprecipitation represent the 5-HT2C receptor, binding studies of the 5-HT2C ligand [3H]-mesulergine to immunoprecipitates from extracts of pig choroid plexus were performed. We demonstrate the presence of a signal sequence that was cleaved off during membrane insertion resulting in a 38-kDa polypeptide. During further maturation, the receptor was N-glycosylated at two sites via a 48-kDa intermediate. This intermediate was far more abundant in choroid plexus than in hippocampus and may represent an intracellular receptor reserve. After transfection of 5-HT2C cDNAs into cultured cells, polypeptides were observed that differed from the ones found in vivo due to abnormal N-glycosylation and possibly other alterations depending on the system used. Thus the 5-HT2C receptor expressed in cell lines may also differ in function from the receptor in its native tissue.
Abramowski
D
D
Sandoz Pharma Ltd., Preclinical Research, Basel, Switzerland.
Staufenbiel
M
M
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D002831:Choroid Plexus / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D006031:Glycosylation; D006624:Hippocampus / Q000378:metabolism*; D007106:Immune Sera; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D015345:Oligonucleotide Probes / Q000235:genetics; D010446:Peptide Fragments / Q000378:metabolism; D021382:Protein Sorting Signals / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D011985:Receptors, Serotonin / Q000737:chemistry* / Q000378:metabolism*; D013552:Swine; D014018:Tissue Distribution
D007106:Immune Sera; D009419:Nerve Tissue Proteins; D015345:Oligonucleotide Probes; D010446:Peptide Fragments; D021382:Protein Sorting Signals; D011985:Receptors, Serotonin