{'fraction_non_alphanumeric': 0.022928994082840236, 'fraction_numerical': 0.008875739644970414, 'mean_word_length': 5.263888888888889, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
FSH Receptor is Synthesized as a Dimer and Proteolytically Processed at the Cell Surface

Follicle‐stimulating hormone receptor (FSHR), a member of the GPCR superfamily, is present in the plasma membrane of ovarian granulosa cells and testicular Sertoli cells. FSHR ectodomain (FSHRECD) is a weakly associated dimer in the crystal structure of FSH in complex with FSHRECD. There are currently no biochemical data that demonstrate dimerization of FSHR in cell membranes. To test this possibility a FRET assay was used in which an FSHR monoclonal antibody, specific for one epitope of the FSHR, was directly labeled with AlexaFluor 568 or AlexaFluor 647, to serve respectively, as donor and acceptor for FRET measurement. Unoccupied FSHR exhibited a robust average FRET efficiency of 19.13 % ± 7.4 in situ. Co‐immunoprecipitation experiments with FSHR C‐terminally tagged with either a myc or a FLAG epitope indicated that FSHR forms dimers early in receptor biosynthesis. Mature and immature forms of FSHR were observed to co‐immunoprecipitate, and during maturation, FSHR undergoes C‐terminal proteolytic processing. A cell surface immunoprecipitation method showed that FSHR oligomers are also present on the cell surface. These results provide the first evidence for dimers of full length FSHR in situ and for C‐terminal proteolytic clipping of FSHR.