Molecular characterization of a novel cDNA from murine cerebellum, developmental expression, and distribution in brain.

Several novel cDNA clones were previously identified by immunoscreening a cerebellar cDNA expression library derived from heterozygous weaver (wu/+) mice at postnatal day one (P1) with an antigranule cell antiserum. One cDNA, GCAP-8 (granule cell antiserum-positive clone 8) has been further characterized. The 1.1 kb insert is a partial cDNA containing a segment near the 3' end of the full-length cDNA. The 5' end of the GCAP-8 cDNA contains a 259 nucleotide open reading frame (ORF) coding for the last 85 amino acids of the carboxy terminus of the encoded protein. The encoded polypeptide contains two highly hydrophobic segments interrupted by a basic stretch. The carboxy terminus of this protein is cysteine-rich, with 10 cysteine residues among the 85 amino acids. The GCAP-8 cDNA probably represents a single-copy gene. The GCAP-8 gene, designated Gcap1, was mapped to the distal region of mouse chromosome 5 by the analyses of two multilocus crosses. The distribution of the GCAP-8 mRNA in mouse brain was studied by in situ hybridization histochemistry. In the adult mouse brain, strong hybridization was detected in cerebellum, hippocampus, substantia nigra (SN), and cerebral cortex. In mouse cerebellum, hybridization was detected in granule cells, Purkinje cells, and in cells of the deep cerebellar nuclei (DCN). In human cerebellum, hybridization was detected in the granule cell layer. In the mouse, GCAP-8 is expressed at least as early as embryonic day 14 (E14) in the central nervous system (CNS).