[Tissue specificity of the human brain protein D2].

Protein D2 was isolated and purified from adult human brain by extraction with Triton X-100 as well as by chromatography on phenyl-sepharose, concanavalin A-sepharose, lysine-sepharose and hydroxylapatite. Specific rabbit antisera against purified protein D2 were raised. Crossed and rocket immunoelectrophoresis revealed an immunoreactive protein D2 in the fetal heart, fetal kidney and adult heart (8-15% of total content in adult brain tissue). Rocket-on-line immunoelectrophoresis revealed additionally small amounts of D2-like antigens in adult kidney (12%), adult liver (1.5%), and in adult lung and spleen (less than 1%). The differences in tissue distribution as revealed by rocket-on-line immunoelectrophoresis suggest the existence of special D2-like protein clone in some tissues with or several immunochemically identical domains.