A 31,000-dalton protein released by cultured human retinal pigment epithelium.
Confluent primary cultures of human retinal pigment epithelium (RPE) were incubated for 3-14 hr with 35S-methionine, 3H-leucine, or 2-3H-mannose, and the released proteins were analyzed by SDS-polyacrylamide gel electrophoresis. A 31,000-dalton protein constituted 10-70% of the released radioactive proteins. The peak was degraded by pronase and its synthesis was inhibited by cycloheximide. The incorporation of 2-3H-mannose into this protein, and its inhibition by tunicamycin, showed that the protein is glycosylated. Monensin (10(-5) M) also inhibited the release of the 31,000-dalton glycoprotein. The released 31,000-dalton glycoprotein from human RPE comigrated on gels with a protein present in extracts of human interphotoreceptor matrix, raising the possibility that the released protein corresponds to a component of the matrix.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D046508:Culture Techniques; D003513:Cycloheximide / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D008875:Middle Aged; D008970:Molecular Weight; D008985:Monensin / Q000494:pharmacology; D010786:Photoreceptor Cells / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D014415:Tunicamycin / Q000494:pharmacology
D005136:Eye Proteins; D014415:Tunicamycin; D008985:Monensin; D003513:Cycloheximide