The purification and characterization of a Thy-1-like glycoprotein from chicken brain

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Abstract
From chicken forebrain a membrane glycoprotein was purified that is enriched in purified synaptic membranes and has an apparent MW of 22,800 in 15% sodium dodecyl sulfate/polyacrylamide gels. This molecule was compared with rat and human brain Thy-1 glycoproteins purified by the same procedure in order to determine whether it could be a homologue of Thy-1. Although polyvalent heterologous antisera raised against the rat and chicken molecules showed no immunological cross-reactivity with the other glycoprotein, a great deal of physical and chemical similarity was demonstrated between the chicken glycoprotein and rat Thy-1. Their apparent MW, subcellular localization and amino acid and amino sugar compositions are very similar. C.d. [circular dichroism] spectra show that both molecules contain predominantly a .beta.-sheet and structure with no detectable .alpha.-helix. Electrophoretic analysis of the CNBr-cleaved molecules under reducing and non-reducing conditions shows that both molecules contain intramolecular disulfide bridges. The chicken brain glycoprotein is apparently an immunologically distinct homologue of the mammalian Thy-1 glycoproteins.