At rest and during exercise carbohydrate and fat are the predominant substrates. They are oxidized simultaneously but the relative contribution of these two substrates is dependent on a variety of factors including the exercise intensity and duration, diet, environmental conditions and training status. Changes in carbohydrate metabolism during the transition from rest to exercise and from low- ...

This study aims at improving the understanding of mechanisms responsible for cell sensitivity to extracellular environment. We explain how substrate mechanical properties can modulate the force regulation of cell sensitive elements primarily adhesion sites. We present a theoretical and experimental comparison between two radically different approaches of the force regulation of adhesion sites t...

determination of streptokinase activity is usually accomplished through two assay methods: a) clot lysis, b) chromogenic substrate assay. in this study the biological activity of two streptokinase products, namely streptase®, which is a native product and heberkinasa®, which is a recombinant product, was determined against the third international reference standard using the two forementioned a...

ADP-glucose pyrophosphorylase (AGPase) is the first rate limiting enzyme of starch biosynthesis pathway and has been exploited as the target for greater starch yield in several plants. The structure-function analysis and substrate binding specificity of AGPase have provided enormous potential for understanding the role of specific amino acid or motifs responsible for allosteric regulation and c...

Background Bile salts undergo enterohepatic circulation which is essential for bile salt homeostasis. From the biliary tract, they are excreted into the small intestine, absorbed into the blood and transported back to the liver. The sinusoidal uptake systems of the liver efficiently extract bile salts and other substrates from portal blood. In rat liver, these systems include Ntcp (sodium tauro...

The closely related G protein-coupled receptor kinases GRK2 and GRK3 are both expressed in cardiac myocytes. Although GRK2 has been extensively investigated in terms of regulation of cardiac beta-adrenergic receptors, the substrate specificities of the two GRK isoforms at G protein-coupled receptors (GPCR) are poorly understood. In this study, the substrate specificities of GRK2 and GRK3 at GPC...

A structural basis for activation and substrate specificity of src tyrosine kinases, and regulation of protein-protein association by tyrosine phosphorylation is described. Lyn, a src-family tyrosine kinase, recognizes and phosphorylates the immunoreceptor tyrosine-based activation motif, ITAM, a critical component in transmembrane signal transduction in hemopoietic cells. The structure of an I...

SCF (Skp1-Cullin-F-box) ubiquitin ligases comprise several dozen modular enzymes that have diverse roles in biological regulation. SCF enzymes share a common catalytic core containing Cul1⋅Rbx1, which is directed toward different substrates by a variable substrate receptor (SR) module comprising 1 of 69 F-box proteins bound to Skp1. Despite the broad cellular impact of SCF enzymes, important qu...

When cells are starved of their substrate, many nutrient transporters are induced. These undergo rapid endocytosis and redirection of their intracellular trafficking when their substrate becomes available again. The discovery that some of these transporters also act as receptors, or transceptors, suggests that at least part of the sophisticated controls governing the trafficking of these protei...

Hepatic glucose and lipid metabolism are altered in metabolic disease (e.g. obesity, metabolic syndrome, and Type 2 diabetes). Insulin-dependent regulation of glucose metabolism is impaired. In contrast, lipogenesis, hypertriglyceridemia, and hepatic steatosis are increased. Because insulin promotes lipogenesis and liver fat accumulation, to explain the elevation in plasma and tissue lipids, in...