title: Structural characterization of an Lyt-2/3 homolog expressed on Bufo regularis lymphocytes.
abstract: Two alloantisera and a monoclonal antibody (mAb 53-6.7) of proven specificities to the murine Lyt-2/3 macromolecule labeled, in indirect immunofluorescent assays, a distinct lymphocyte population in the toad, Bufo regularis. Lyt-2/3 antigenic activities expressed by B. regularis lymphocytes have been solubilized and purified by mAb 53-6.7 affinity chromatography and found to be associated with a single 67 kDa macromolecule in SDS-PAGE. Upon reduction, this macromolecule resolved into 38 kDa, 34 kDa and 28 kDa subunits corresponding to the alpha, alpha' and beta subunits of the murine Lyt-2/3 complex. Comparisons based on the S delta Q index of differences in amino acid compositions of HPLC-purified alpha- and alpha'-subunits of the amphibian Lyt-2/3 molecule indicated a significant structural relatedness to their murine counterpart as well as to the human CD8 polypeptide. Our observations point to an early phylogenetic emergence of Lyt-2/3 as an important component of the T cell cytolytic apparatus during vertebrate evolution.
authors.affiliation: Department of Zoology, Monofia University, Cairo, Egypt.
authors.forename: H I
authors.initials: HI
authors.lastname: Negm
authors.forename: M H
authors.initials: MH
authors.lastname: Mansour
authors.forename: A H
authors.initials: AH
authors.lastname: Saad
authors.forename: R S
authors.initials: RS
authors.lastname: Abdel Halim
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D000911:Antibodies, Monoclonal; D000950:Antigens, Ly / Q000097:blood*; D002025:Bufonidae / Q000276:immunology*; D005260:Female; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D051379:Mice; D008970:Molecular Weight; D017386:Sequence Homology, Amino Acid
chemical_list: D000596:Amino Acids; D000911:Antibodies, Monoclonal; D000950:Antigens, Ly