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991.
A comparative analysis of the individual and joint influence of bovine prolactin (BPRL) and bovine somatotropin (BST) on DNA synthesis in cultured bovine granulosa cells from follicles of 3-5 mm in diameter was conducted, and a possibility for regulation of BPRL binding to receptors on the cells by BST was examined. Despite a unidirectional growth-promoting action of BPRL and BST on granulosa cells, their joint mitogenic effect on the cells was not additive at low concentrations of BPRL. The addition of BST to the culture medium did not alter the biphasic character of dependence of DNA synthesis in the cells on BPRL concentration, but increased the maximum effective concentration of the latter. When culturing granulosa cells with BST, the absence of its influence on the level of BPRL specific binding to the cells was shown. This fact suggests that BST modulating action on the mitogenic effect of BPRL is not a result of a change in the number of free receptors for PRL on granulosa cells. The results obtained are discussed in relation to the notion of similarity of receptor functional properties and intracellular signal ways for PRL and ST. 相似文献
992.
Nemirovskaia TL Shenkman BS Mazin MG Koshelev VB Maevskiĭ EI Grishina E 《Tsitologiia》2000,42(1):79-83
It is known that a long-duration decline of high-energy phosphate (HP) level in skeletal muscles, induced by administration of beta-guanidinpropionic acid (beta-GPA), is followed by an increase in mitochondrial enzyme activities (MEA). The same increase in MEA was observed in the course of physical exercise training. Under gravitational inloading decrease in MEA and increase in the level of high-energy phosphates occurred. If changes in (HP) level are believed to trigger the alterations in MEA, the increase in high-energy phosphate levels in muscles is to lead to a decline in MEA as well. The present work was purposed to reveal if changes in HP level under different contractile activity levels may be associated with changes in oxidative potential in the skeletal muscles. 相似文献
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Uverskiĭ VN Permiakov SE Senin II Cherskaia AM Shul'ga-Morskoĭ SV Zinchenko DV Alekseev AM Zargarov AA Lipkin VM Filippov PP Permiakov EA 《Bioorganicheskaia khimiia》2000,26(3):173-178
The structural properties of myristoylated forms of recombinant recoverin of the wild type and of its mutants with damaged second and/or third Ca(2+)-binding sites were studied by fluorimetry and circular dichroism. The interaction of wild-type recoverin with calcium ions was shown to induce unusual structural rearrangements in its molecule. In particular, protein binding with Ca2+ ions results in an increase in the mobility of the environment of Trp residues, in higher hydrophobicity, and in elevated thermal stability (its thermal transition shifts by 15 degrees C to higher temperatures) but has almost no effect on its secondary structure. Similar structural changes induced by Ca2+ are also characteristic of the -EF2 mutant of recoverin whose second Ca(2+)-binding site is modified and cannot bind calcium ions. The structural properties of the -EF3 and -EF2,3 mutants (whose third or simultaneously second and third Ca(2+)-binding sites, respectively, are modified and damaged) are practically indifferent to calcium ions. 相似文献