STRUCTURE AND CELLULAR-DISTRIBUTION OF MOUSE-BRAIN TESTICAN - ASSOCIATION WITH THE POSTSYNAPTIC AREA OF HIPPOCAMPUS PYRAMIDAL CELLS

The complete deduced primary structure of mouse brain testican has bee n established from cDNA cloning. The cDNA encodes a polypeptide of 442 amino acids belonging to the proteoglycan family. The mouse brain tes tican core protein is 95% identical to its human testicular counterpar t. In situ hybridization investigations revealed that mouse testican m RNA is mainly present in a subpopulation of pyramidal neurons localize d in the CA3 area of the hippocampus. An immunocytochemical approach, with antibodies directed against an overexpressed chimeric antigen, pr oduced in bacterial systems, showed that testican is associated with t he postsynaptic region of these pyramidal neurons. Testican includes s everal putative functional domains related to extracellular or pericel lular proteins associated with binding and/or regulatory functions. On the basis of its structural organization and its occurrence in postsy naptic areas, this proteoglycan might contribute to various neuronal m echanisms in the central nervous system.