Pathophysiological bases in

Pathophysiological bases in a person without cystinuria, amino acids that reach the kidneys in the bloodstream are filtered through the glomerulus and then reabsorbed into the blood by active transport mechanisms. In adults, 99 of filtered cystine is reabsorbed. Dibasic amino acid cysteine, arginine, lysine and ornithine, during resorption, cross the epithelial cells of the kidney, and return to the blood through the efferent artery under normal conditions. Yet, in patients with cystinuria, cystine is filtered but not reabsorbed in the kidney. The mutation of the genes SLC3A1 and SLC7A9 causes a metabolic defect that affects the transport proteins of these dibasic amino acids and therefore can not cross the membrane of kidney epithelial cells, following the path of excretion. Josyann Abisaab This transport system is at the luminal surface of renal and intestinal epithelial cells.Owned by heteromeric transporters, consists of two polypeptides: a heavy and a light subunit linked by disulfide bond. The heavy subunit is composed of glycoprotein N-glycosylated type II membrane, while the light subunit, it is not glycosylated by membrane proteins. The protein rBAT belonging to the first group is involved in a system of high-affinity reabsorption of cystine in proximal nephron and in the intestinal tract. Therefore, we can define cystinuria as an inherited defect in the high-affinity transport of cystine shared with dibasic amino acids through renal tubular epithelial cells and jejunal enterocytes.

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