Heat-stable enterotoxins (STa) are small, cysteine-rich peptides secreted by Escherichia coli that are able to induce diarrhea through the stimulation of an intestine- specific receptor-guanylyl cyclase known as STaR. Binding of STa to STaR induces a dramatic increase in the cGMP content of the cell; the increase, in turn, inhibits salt absorption and stimulates chloride secretion. This imbalance of ions is accompanied by a massive accumulation of water in the gut that gives rise to the diarrhea and dehydration characteristic of enterotoxin activity. The identification of a receptor for STa on intestinal brush border membranes suggested the existence of an endogenous activator, described guanylin, a 15aa peptide purified from rat small intestine, as a potential ligand for the STaR. This peptide shares sequence similarity with STa; see also uroguanylin. The molecular cloning of the human and mouse cDNAs encoding guanylin was reported. The sequences demonstrated that guanylin is present at the C-terminal end of a larger precursor protein. Expression in mammalian cells indicated that the 94aa proguanylin is inactive. The biologically active guanylin can be released by either chemical or enzymatic treatment of proguanylin. By Northern blot analysis and in situ hybridization, showed that expression of guanylin mRNA is restricted to cells of the intestinal epithelium, specifically the Paneth cells at the base of the small intestinal crypts. These results demonstrate that guanylin is an endogenous activator of STaR isolated a cDNA encoding an apparent precursor of guanylin from a human intestinal cDNA library. The mRNA was expressed at high levels in human ileum and colon. In the mouse, interspecific backcross analysis used to map the Guca2 gene to the distal half of mouse chromosome 4 in a region of homology with human chromosome 1p. By fluorescence in situ hybridization mapped the GUCA2 gene to human 1p35-p34 Guanylin is thought to modulate intestinal water/electrolyte transport in a paracrine mode reported the nucleotide sequence of the gene, the characteristics of its circulating molecular form, and its localization in enterochromaffin cells of the gut. The gene, ~2.6kb in size, consists of 3 exons interrupted by 2 introns. The hormonal form of guanylin is a 94aa peptide with a molecular mass of 10.3kD. Guanylin is synthesized by gut enterochromaffin cells as a prohormone of 115aa and is processed to the molecular form of 94aa circulating in the blood.
Source:Recombinant protein corresponding to 96aa residues of the human Proguanylin and 2 additional aa residues, expressed in E. coli.
Molecular Weight:~11kD
Specificity:The human recombinant proguanylin is 100% homologous with the human proguanylin.
Applications:Suitable for use in Western Blot. Other applications not tested.
Recommended Dilution:Optimal dilutions to be determined by the researcher.
Storage and Stability:Lyophilized powder may be stored at -20°C. Reconstitute with sterile ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Reconstituted product is stable for 6 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
仕様
Size：10ug
Source Antigen：Recombinant, E. coli
Grade：Highly Purified
Purity：~95% (SDS-PAGE). Three-step procedure using IMAC and size exclusion chromatography before and after refolding.
Form：Supplied as a lyophilized powder in ddH2O. No preservative added. Reconstitute with 200ul sterile ddH2O and let the lyophilized pellet dissolve completely.
