Different processing of LH/hCG receptors in cultured rat luteal cells and murine Leydig tumor cells (MLTC-1)

Journal Article · Sat Jan 31 23:00:00 EST 1987 · Exp. Cell Res.; (United States)

DOI:https://doi.org/10.1016/0014-4827(87)90002-4· OSTI ID:6524469

Kellokumpu, S

The metabolic fate of LH/hCG receptors after exposure to human chorionic gonadotropin (hCG) was examined in cultured rat luteal cells and murine Leydig tumor cells (MLTC-1). Kinetic studies performed after pulse-labelling of the cells with (/sup 125/I)hCG indicated that the bound hormone was lost much more rapidly from the tumor cells than from the luteal cells. The tumor cells were also found to internalize and degrade the hormone more effectively than the luteal cells. Chemical cross-linking and analyses by SDS-PAGE of this material revealed that both cell types also released, in addition to intact hCG, two previously characterized receptor fragment-(/sup 125/I)hCG complexes (M/sub r/ 96,000 and 74,000) into the medium, although their amount was negligible in MLTC-1 cells. Possibly due to rapid discharge of the ligand from its receptor, no similar complexes could be detected inside the MLTC-1 cells, suggesting that they were released directly from the cell surface. However, the M/sub r/ 74,000 complex was observed inside MLTC-1 cells if chloroquine, a lysosomotropic agent, was present during the incubations. This suggests that the internalized receptor also becomes degraded, at least when complexed to hCG. The results thus provide evidence that there exist two different mechanisms for proteolytic processing of LH/hCG receptors in these target cells. In tumor cells, the degradation seems to occur almost exclusively intracellularly, whereas in luteal cells a substantial portion of the receptors is also degraded at the cell surface.

• Research Organization: Univ. of Oulu, Finland
• OSTI ID: 6524469
• Journal Information: Exp. Cell Res.; (United States), Journal Name: Exp. Cell Res.; (United States) Vol. 168:2; ISSN ECREA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ALKALI METAL COMPOUNDS
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BODY
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELECTROPHORESIS
FEMALE GENITALS
GONADOTROPINS
GONADS
HALIDES
HALOGEN COMPOUNDS
HCG
HORMONES
INORGANIC PHOSPHORS
INTERMEDIATE MASS NUCLEI
IODIDES
IODINE 125
IODINE COMPOUNDS
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MEMBRANE PROTEINS
MICE
MOLECULAR STRUCTURE
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
OVARIES
PEPTIDE HORMONES
PHOSPHORS
PITUITARY HORMONES
PROTEINS
RADIOISOTOPES
RADIORECEPTOR ASSAY
RATS
RECEPTORS
RODENTS
SODIUM COMPOUNDS
SODIUM IODIDES
TRACER TECHNIQUES
TUMOR CELLS
VERTEBRATES