摘要:

AbstractAntiviral activities of known protease inhibitors were assayed in virus‐infected cell cultures. Some members of the cystatin superfamily, in particular chicken cystatin, were able to block virus replication. In a binding assay, using purified components, chicken and human cystatin were able to bind poliovirus protease with affinities which were reflected in their relative anitviral potencies. Prospects for application of protease inhibitors in clinical viral infections are discusse

ISSN:0730-2312    

DOI:10.1002/jcb.240320202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractA neuronal glycoprotein (GP130) that is associated with the cytoskeleton [Ranscht et al: J Cell Biol 99:1803–1813, 1984] remains insoluble in 0.1 M NaOH, a property typical of integral membrane proteins. At present it is possible to solubilise and hence isolate GP130 only under denaturing conditions. However, a large fragment of apparent molecular weight 120K is released into solution by trypsin. The fragment corresponds to the extracellular region of the glycoprotein as shown by the fact that it is released from live cultures of chicken sympathetic neurons and by its retention of concanavalin A‐binding activity. The soluble extracellular fragment has been purified using mild biochemical techniques, which are expected to retain its biological activity. Measurement of the sedimentation coefficient, Stokes radius, and frictional ratio in addition to metal shadowing of the fragment show that it has a molecular weight of about 120K and is asymmetric, probably rod‐shaped with a long axis of more than

ISSN:0730-2312    

DOI:10.1002/jcb.240320203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractA tyrosine protein kinase activity has been detected in the mitochondrial fraction purified from human fibroblasts. By enzymatic and sedimentation analysis this activity appeared to be localized in the mitochondrial outer membrane. Mitochondrial tyrosine phosphorylation was strictly dependent on the presence of Mn2+ions. An inverse relationship between cell proliferation and mitochondrial protein phosphorylation on tyrosine residues has been found: a marked increase in the mitochondrial tyrosine kinase activity occurred when a significant reduction in the growth rate followed serum step‐down. In mitochondria purified from resting cells, a protein band with apparent molecular weight of 50 kd appeared to be phosphorylated on tyrosin

ISSN:0730-2312    

DOI:10.1002/jcb.240320204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractIntact embryonic chick neural retina cells have at their surface an N‐acetylgalactosaminyltransferase which catalyzes the incorporation of N‐acetylgalactosamine from UDP‐N‐acetylgalactosamine into endogenous macromolecular acceptors. The enzyme along with its endogenous acceptors can be isolated as a particulate complex following treatment of membrane‐enriched fractions with Triton X‐100. In this paper we report on two separate fusions generating monoclonal antibodies: one using as immunogen the particulate complex and the second using as immunogen a soluble N‐acetylgalactosaminyltransferase found in tissue‐culture‐conditioned medium which lacks endogenous acceptor activity. Antibodies from both fusions recognize an antigen which is tightly associated with the particulate transferase/acceptor complex and a soluble antigen having N‐acetyl‐galactosaminyltransferase activity toward exogenously added acceptors. The antibodies recognize a component of ca Mr220,000, which shows N‐acetylgalactosaminyltransferase activity after SDS‐gel electrophoresis and transfer to nitrocellulose. This component comigrates on two‐dimensional gel electrophoresis with an iodinatable cell surface component whose presence at the cell surface correlates with endogenous transferase activity. We conclude that the antibodies recognize the transferase enzyme itself. Immunohistochemical analysis shows that the enzyme is initially localized throughout the embryonic neural retina in a pattern indicative of a cell surface disposition but becomes restricted to the outer plexiform layer and to

ISSN:0730-2312    

DOI:10.1002/jcb.240320205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe effect of glucose and calcium on the activities of the phosphatidylinositol cycle enzymes, CDP‐diglyceride inositol transferase, diacylglycerokinase, and lysophosphatidylcholine 2‐acyltransferase in rat pancreatic islets was studied. Calcium inhibited the activity of CDP‐diglyceride inositol transferase but had no effect on lysophosphatidylcholine 2‐acyltransferase and diacylglycerokinase activites. Upon preincubation of islets in a concentration of glucose known to stimulate insulin release, the activity of lysophosphatidylcholine 2‐acyltransferase, but not that of diacylglycerokinase or the CDP‐diglyceride inositol transferase, was stimulated. Subcellular fractionation of pancreatic islets showed that secretory granule membranes were enriched in CDP‐diglyceride inositol transferase, whereas lyso‐phosphatidylcholine 2‐acyltransferase activity was highest in the microsomal membranes. The activation of 2‐acyltransferase by incubating islets in insulinotropic glucose, and the calcium sensitivity of CDP‐diglyceride inositol transferase, suggest that these enzymes may have roles in regulation

ISSN:0730-2312    

DOI:10.1002/jcb.240320206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0730-2312    

DOI:10.1002/jcb.240320207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0730-2312    

DOI:10.1002/jcb.240320201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY