title: Membrane immunoglobulin is characterized by distinct structural subpopulations.
abstract: Membrane immunoglobulins are integral proteins on B cell surfaces that bind foreign antigens and are critically involved in the regulation of the immune response. Based upon the model of serum IgG, it has been assumed that membrane immunoglobulins are essentially four chain disulfide-linked structures of the form H2L2, where H represents an immunoglobulin heavy chain, and L a light chain. We show here that membrane immunoglobulins of the mu and delta isotypes are present on spleen cell surfaces in a much more diverse group of disulfide linked structures. In some cases mIg is linked into structures as large as H5L5, while in other instances mu or delta chains appear to be linked by disulfide interactions to non-immunoglobulin molecules. These various structural complexes may represent distinct functional entities, as the association of mIg with the cytoskeleton after mIg cross-linking appears to depend upon its structural subgroup.
authors.affiliation: Department of Biological Sciences, Wayne State University, Detroit, MI 48202.
authors.forename: S
authors.initials: S
authors.lastname: Alhasan
authors.forename: R
authors.initials: R
authors.lastname: Santini
authors.forename: Q
authors.initials: Q
authors.lastname: Li
authors.forename: A
authors.initials: A
authors.lastname: Rosenspire
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry; D005260:Female; D007143:Immunoglobulin Heavy Chains / Q000737:chemistry; D007138:Immunoglobulin delta-Chains / Q000737:chemistry; D007148:Immunoglobulin mu-Chains / Q000737:chemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008970:Molecular Weight; D011487:Protein Conformation; D011947:Receptors, Antigen, B-Cell / Q000737:chemistry* / Q000302:isolation & purification; D013154:Spleen / Q000737:chemistry
chemical_list: D004220:Disulfides; D007143:Immunoglobulin Heavy Chains; D007138:Immunoglobulin delta-Chains; D007148:Immunoglobulin mu-Chains; D011947:Receptors, Antigen, B-Cell