Biomaterial Database

The carboxy-terminal region of the glycoprotein hormone alpha-subunit: contributions to receptor binding and signaling in human chorionic gonadotropin. 1992

F Chen, and Y Wang, and D Puett

Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Florida 33101.

The glycoprotein hormones are heterodimeric and contain a common alpha-subunit, which is noncovalently associated with a hormone-specific beta-subunit. The alpha-subunit has been highly conserved throughout evolution; for example, the five amino acid residues of the carboxy-terminus, Tyr-Tyr-His-Lys-Ser-COOH, are identical in nine of the 10 available amino acid sequences. It has been shown that enzymatic removal of these five amino acid residues, while not affecting holoprotein formation, results in a heterodimer that exhibits very little, if any, binding to the CG/LH receptor. Using site-directed mutagenesis on the human alpha-subunit, we have prepared two deletion mutants, Des-(88-92)alpha and Des-(89-92)alpha, and two point mutants, where each of the two tyrosines, 88 and 89, was replaced with phenylalanine, in order to delineate more specifically the contributions of these aromatic side-chains to receptor binding. The cDNAs for wild-type hCG alpha and mutants were introduced into a pcDNAINEO expression vector, and the cDNA for hCG beta was inserted into a pRSV plasmid; both were transiently cotransfected into DUXB-11 cells. The media were collected, and RIAs showed that all mutants formed heterodimers; moreover, there was no discernable difference in subunit assembly between wild-type hCG alpha and the various mutant alpha-subunits. The gonadotropin mutants were assayed in vitro using a competitive binding assay with [125I]hCG and stimulation of progesterone production in the transformed murine Leydig cell line MA-10.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D007985	Leydig Cells	Steroid-producing cells in the interstitial tissue of the TESTIS. They are under the regulation of PITUITARY HORMONES; LUTEINIZING HORMONE; or interstitial cell-stimulating hormone. TESTOSTERONE is the major androgen (ANDROGENS) produced.	Interstitial Cells, Testicular,Leydig Cell,Testicular Interstitial Cell,Testicular Interstitial Cells,Cell, Leydig,Cell, Testicular Interstitial,Cells, Leydig,Cells, Testicular Interstitial,Interstitial Cell, Testicular
D008297	Male		Males
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D010446	Peptide Fragments	Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.	Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D011374	Progesterone	The major progestational steroid that is secreted primarily by the CORPUS LUTEUM and the PLACENTA. Progesterone acts on the UTERUS, the MAMMARY GLANDS and the BRAIN. It is required in EMBRYO IMPLANTATION; PREGNANCY maintenance, and the development of mammary tissue for MILK production. Progesterone, converted from PREGNENOLONE, also serves as an intermediate in the biosynthesis of GONADAL STEROID HORMONES and adrenal CORTICOSTEROIDS.	Pregnenedione,Progesterone, (13 alpha,17 alpha)-(+-)-Isomer,Progesterone, (17 alpha)-Isomer,Progesterone, (9 beta,10 alpha)-Isomer
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011974	Receptors, LH	Those protein complexes or molecular sites on the surfaces and cytoplasm of gonadal cells that bind luteinizing or chorionic gonadotropic hormones and thereby cause the gonadal cells to synthesize and secrete sex steroids. The hormone-receptor complex is internalized from the plasma membrane and initiates steroid synthesis.	Chorionic Gonadotropin Receptors,Human Chorionic Gonadotropin Receptors,ICSH Receptors,LH Receptors,LH-hCG Receptor,LH-hCG Receptors,Luteinizing Hormone Receptors,Lutropin Receptor,Lutropin Receptors,Receptors, Chorionic Gonadotropin,Receptors, Human Chorionic Gonadotropin,Receptors, Interstitial Cell-Stimulating Hormone,Receptors, Luteinizing Hormone,hCG Receptors,Chorionic Gonadotropin Receptor,Human Chorionic Gonadotropin Receptor,LH Receptor,Luteinizing Hormone Receptor,Receptors, ICSH,Receptors, Interstitial Cell Stimulating Hormone,Receptors, LH-hCG,Receptors, Lutropin,Receptors, hCG,hCG Receptor,Gonadotropin Receptor, Chorionic,Gonadotropin Receptors, Chorionic,Hormone Receptor, Luteinizing,Hormone Receptors, Luteinizing,LH hCG Receptor,LH hCG Receptors,Receptor, Chorionic Gonadotropin,Receptor, LH,Receptor, LH-hCG,Receptor, Luteinizing Hormone,Receptor, Lutropin,Receptor, hCG,Receptors, LH hCG
D011993	Recombinant Fusion Proteins	Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.	Fusion Proteins, Recombinant,Recombinant Chimeric Protein,Recombinant Fusion Protein,Recombinant Hybrid Protein,Chimeric Proteins, Recombinant,Hybrid Proteins, Recombinant,Recombinant Chimeric Proteins,Recombinant Hybrid Proteins,Chimeric Protein, Recombinant,Fusion Protein, Recombinant,Hybrid Protein, Recombinant,Protein, Recombinant Chimeric,Protein, Recombinant Fusion,Protein, Recombinant Hybrid,Proteins, Recombinant Chimeric,Proteins, Recombinant Fusion,Proteins, Recombinant Hybrid
D002461	Cell Line, Transformed	Eukaryotic cell line obtained in a quiescent or stationary phase which undergoes conversion to a state of unregulated growth in culture, resembling an in vitro tumor. It occurs spontaneously or through interaction with viruses, oncogenes, radiation, or drugs/chemicals.	Transformed Cell Line,Cell Lines, Transformed,Transformed Cell Lines
D004247	DNA	A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).	DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA