Some of the mutations were naturally occurring and resulted in either constitutive activation or loss-of-function of LHR, while many of the loss-of-function mutants have been identified by site-directed mutagenesis. buy ortho tri-cyclen
Elucidation of the genomic structure of the LHR gene led to the suggestion of a possible origin of the putative ancestral glycoprotein hormone receptor gene. The LHR gene contains 10 exons that encode most of the ECD and one exon (no. 11) that encodes a small portion of the ECD, the seven transmembrane helices, the six connecting loops, and the cytoplasmic tail. It appears that exons 1-10, with the corresponding introns, were added to an intronless GPCR gene, probably of the adrenergic family, to form an early gene for a heptahelical receptor with a relatively large ECD.
Using the power inherent in protein engineering, we and others have prepared and characterized single-chain forms of hCG in which the C-terminus of hCG0, full-length and various truncated forms, was fused to the N-terminus of full-length and truncated human a, or in which intersubunit disulfides were engineered. These yoked or tethered molecules offer many advantages over heterodimers for detailed structure-function studies; moreover, they have the potential for clinical applications in view of their greater stability. Continuing our studies with yoked hCG, we have also prepared and characterized yoked hCG-LHR complexes, as well as yoked subunit-LHR complexes (Fig. 2). This minireview will focus on this new area in hCG and LHR research.
FIG. 2. Schematics of the yoked constructs discussed in this paper. Yoked hCG (YhCG) was expressed in baculovirus-infected insect cells; yoked hCG-LHR (YHR) was expressed in COS-7 and in HEK 293 cells; and yoked human a-LHR (YaR) and yoked hCGp-LHR (YfiR) were expressed in HEK 293 cells. SS„ and SSa denote the signal sequences of the hCGp and the human a (ha) subunits, respectively; hCG0 refers to the full-length polypeptide chain, including the С-terminal peptide (CTP); an additional CTP is present in the Y|3R.