Show simple item record

dc.contributor.authorNguyen, Quoc V.
dc.contributor.authorHumphreys, Robert E.
dc.date2022-08-11T08:10:05.000
dc.date.accessioned2022-08-23T16:54:37Z
dc.date.available2022-08-23T16:54:37Z
dc.date.issued1989-01-25
dc.date.submitted2008-08-15
dc.identifier.citationJ Biol Chem. 1989 Jan 25;264(3):1631-7.
dc.identifier.issn0021-9258 (Print)
dc.identifier.pmid2783582
dc.identifier.urihttp://hdl.handle.net/20.500.14038/42544
dc.description.abstractTo determine how changing forms of class II major histocompatibility complex proteins and associated Ii molecules in intracellular compartments of human B lymphocytes might regulate or catalyze antigen processing or presentation, we analyzed immunoprecipitates of such molecules from subcellular fractions of [35S]methionine pulse-chase-labeled, 3-day-activated B lymphocytes after homogenization and distribution in Percoll density gradients. Two-dimensional gel electrophoresis of immunoprecipitates of subcellular fractions demonstrated: 1) progressive sialic acid addition to class II major histocompatibility complex beta chains and Ii but not to gamma 2, gamma 2', gamma 3, gamma 3' (p35), or p41 and its satellites; 2) association of p35 and p41 with class II complexes at 30-60 min after pulse labeling; 3) cleavage of an immature form of Ii without sialic acid at 15-30 min after pulse labeling to a COOH-terminal, 25,000-dalton fragment, p25, with a 60-90-min half-life; 4) the presence of Ii-related p29 at only 30-min chase times; 5) an effect of chloroquine or monensin, at maximal nontoxic doses, to increase (a) the time for associations of p35 and p41 with class II complexes and (b) the half-life of p25, which was then formed from Ii at reduced levels. In addition, while the half-lives of class II alpha and beta chains and Ii were comparable within intracellular fractions of any one density, in intracellular fractions of intermediate densities the complexes appeared to be longer lived (much greater than 6 h) than in lighter fractions (2-3-h half-lives).
dc.language.isoen_US
dc.relation<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&list_uids=2783582&dopt=Abstract">Link to Article in PubMed</a>
dc.relation.urlhttp://www.jbc.org/cgi/reprint/264/3/1631
dc.subjectB-Lymphocytes
dc.subjectCell Compartmentation
dc.subjectCentrifugation, Density Gradient
dc.subjectHalf-Life
dc.subjectHistocompatibility Antigens Class I
dc.subjectHistocompatibility Antigens Class II
dc.subjectHumans
dc.subjectMethionine
dc.subjectMonensin
dc.subjectN-Acetylneuraminic Acid
dc.subjectProtein Processing, Post-Translational
dc.subjectSialic Acids
dc.subjectTime Factors
dc.subjectLife Sciences
dc.subjectMedicine and Health Sciences
dc.titleTime course of intracellular associations, processing, and cleavages of Ii forms and class II major histocompatibility complex molecules
dc.typeJournal Article
dc.source.journaltitleThe Journal of biological chemistry
dc.source.volume264
dc.source.issue3
dc.identifier.legacycoverpagehttps://escholarship.umassmed.edu/oapubs/883
dc.identifier.contextkey579772
html.description.abstract<p>To determine how changing forms of class II major histocompatibility complex proteins and associated Ii molecules in intracellular compartments of human B lymphocytes might regulate or catalyze antigen processing or presentation, we analyzed immunoprecipitates of such molecules from subcellular fractions of [35S]methionine pulse-chase-labeled, 3-day-activated B lymphocytes after homogenization and distribution in Percoll density gradients. Two-dimensional gel electrophoresis of immunoprecipitates of subcellular fractions demonstrated: 1) progressive sialic acid addition to class II major histocompatibility complex beta chains and Ii but not to gamma 2, gamma 2', gamma 3, gamma 3' (p35), or p41 and its satellites; 2) association of p35 and p41 with class II complexes at 30-60 min after pulse labeling; 3) cleavage of an immature form of Ii without sialic acid at 15-30 min after pulse labeling to a COOH-terminal, 25,000-dalton fragment, p25, with a 60-90-min half-life; 4) the presence of Ii-related p29 at only 30-min chase times; 5) an effect of chloroquine or monensin, at maximal nontoxic doses, to increase (a) the time for associations of p35 and p41 with class II complexes and (b) the half-life of p25, which was then formed from Ii at reduced levels. In addition, while the half-lives of class II alpha and beta chains and Ii were comparable within intracellular fractions of any one density, in intracellular fractions of intermediate densities the complexes appeared to be longer lived (much greater than 6 h) than in lighter fractions (2-3-h half-lives).</p>
dc.identifier.submissionpathoapubs/883
dc.contributor.departmentDepartment of Pediatrics
dc.source.pages1631-7


This item appears in the following Collection(s)

Show simple item record