1.
ATP-binding cassette (ABC) transporters in human metabolism and diseases.
Stefková, J, Poledne, R, Hubácek, JA
Physiological research. 2004;(3):235-43
Abstract
The ATP-binding cassette (ABC) superfamily of active transporters involves a large number of functionally diverse transmembrane proteins. They transport a variety of substrates including amino acids, lipids, inorganic ions, peptides, saccharides, metals, drugs, and proteins. The ABC transporters not only move a variety of substrates into and out of the cell, but also are also involved in intracellular compartmental transport. Energy derived from the hydrolysis of ATP is used to transport the substrate across the membrane against a concentration gradient. The typical ABC transporter consists of two transmembrane domains and two nucleotide-binding domains. Defects in 14 of these transporters cause 13 genetic diseases (cystic fibrosis, Stargardt disease, adrenoleukodystrophy, Tangier disease, etc.). Mutations in three genes affect lipid levels expressively. Mutations in ABCA1 cause severe HDL deficiency syndromes called Tangier disease and familial high-density lipoprotein deficiency, which are characterized by a severe deficiency or absence of high-density lipoprotein in the plasma. Two other ABCG transporters, ABCG5 and ABCG8, mutations of which cause sitosterolemia, have been identified. The affected individuals absorb and retain plant sterols, as well as shellfish sterols.
2.
[The concentration of adenine nucleotides in platelets of patients with primary chronic glomerulonephritis].
Lizakowski, S, Zdrojewski, Z, Jagodziński, P, Słomińska, E, Rutkowski, B
Polskie Archiwum Medycyny Wewnetrznej. 2000;(2):467-73
Abstract
UNLABELLED Nephrotic syndrome (n.s.) is associated with numerous blood coagulation abnormalities and a marked predisposition to thromboembolism. Increased aggregation and activation of platelets in patients with glomerulonephritis (g.l.n. p.t.s.) may partly explain this status. The aim of this study was to measure the platelets adenine nucleotides concentration. The study was performed in 57 patients with a renal biopsy confirmed primary glomerulonephritis and 24 sex and age matched healthy volunteers which served as a control group. The patients were divided into two subgroups: subgroup I/A--36 patients with the symptoms of the nephrotic syndrome and subgroup I/B--21 patients with chronic glomerulonephritis and proteinuria but without the symptoms of nephrotic syndrome. Concentration of adenine nucleotides in platelets was measured using HPLC. In the subgroup I/A significantly lower levels of ATP, ADP and AMP concentrations in platelets were observed comparing to control subjects. Simultaneously significant correlation between both ATP and ADP concentration and plasma levels of albumin, total cholesterol, LDL-cholesterol, triglycerides and fibrinogen were found in g.l.n. p.t.s. SUMMARY AND CONCLUSIONS 1. Significantly lower concentrations of adenine nucleotides in platelets of gln pts with the nephrotic syndrome may result from their activation. 2. Protein and lipid metabolism as well as fibrinogen seem to influence ATP and ADP concentrations in platelets of g.l.n. p.t.s.