Follitropin receptors contain cryptic ligand binding sites.

Human choriogonadotropin (hCG) and follitropin (hFSH) have been shown to contact different regions of the extracellular domains of G-protein coupled lutropin (LHR) and follitropin (FSHR) receptors. We report here that hCG and hFSH analogs interact with different regions of an FSHR/LHR chimera having only two unique LHR residues and that binds both hormones with high affinity. hCG and hFSH analogs dock with this receptor chimera in a manner similar to that in which they bind LHR and FSHR, respectively.

Tight attachment of chitin-binding-domain-tagged proteins to surfaces coated with acetylated chitosan.

Several excellent procedures for trapping tagged proteins have been devised, but many of these are expensive, cannot be used outside a limited pH range, fail to work in the presence of chaotropic agents, or are difficult to use. The chitin binding domain (CBD) of Bacillus circulans chitinase, which binds to chitin matrices prepared from inexpensive reagents isolated from crab shells, is an alternative tag that can be used under a variety of pH and denaturing conditions. Kits based on the interaction between the CBD and the chitin beads are available commercially.

The surface of alpha-subunit loop 1 distant from the subunit interface is exposed in the hCG lutropin receptor complex.

Interactions of the placental glycoprotein hormone human choriogonadotropin (hCG) with lutropin receptors (LHR) are required for maintenance of early pregnancy. Knowledge of how hCG interacts with LHR is useful for understanding the mechanism of receptor function, an issue of considerable debate. A large surface of hCG remains exposed after the hormone binds the LHR and can be readily detected with monoclonal antibodies.

Addition of an N-terminal dimerization domain promotes assembly of hCG analogs: implications for subunit combination and structure-function analysis.

Human chorionic gonadotropin (hCG) is a heterodimeric placental glycoprotein hormone that acts through ovarian lutropin receptors (LHR) to maintain early pregnancy. Its ability to distinguish LHR and follitropin receptors (FSHR) is controlled by 20 beta-subunit 'seatbelt' residues that surround alpha-subunit loop 2. Positively charged amino acids between residues 93-100, a small loop within the seatbelt, have been postulated to make essential LH receptor contacts.

Fulminant acute colitis following a self-administered hydrofluoric acid enema.

A 33-yr-old white male presented with bloody diarrhea, leukocytosis, and left lower quadrant direct and rebound tenderness after a self-administered concentrated hydrofluoric acid enema while intoxicated from intranasal cocaine administration. Intraoperative flexible sigmoidoscopy and a gastrografin enema revealed severe mucosal ulceration and edema in the rectum and sigmoid colon. Laparotomy revealed an ulcerated, necrotic, and purulent sigmoid colon and intraperitoneal pus.