Hi. Negm et al., STRUCTURAL CHARACTERIZATION OF AN LYT-2 3 HOMOLOG EXPRESSED ON BUFO-REGULARIS LYMPHOCYTES/, Comparative biochemistry and physiology. B. Comparative biochemistry, 113(1), 1996, pp. 79-87
Two alloantisera and a monoclonal antibody (mAb 53-6.7) of proven spec
ificities to the murine Lyt-2/3 macromolecule labeled, in indirect imm
unoflourescent assays, a distinct lymphocyte population in the toad, B
ufo 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 he associated with a single 67 kDa macromo
lecule in SDS-PAGE. Upon reduction, this macromolecule resolved into 3
8 kDa, 34 kDa and 28 kDa subunits corresponding to the alpha, alpha' a
nd beta subunits of the murine Lyt-2/3 complex. Comparisons based on t
he S Delta Q index of differences in amino acid compositions of HPLC-p
urified alpha- and alpha'-subunits of the amphibian Lyt-2/3 molecule i
ndicated a significant structural relatedness to their murine counterp
art 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.