CHARACTERIZATION OF PHOTOLYASE BLUE-LIGHT RECEPTOR HOMOLOGS IN MOUSE AND HUMAN-CELLS/

We isolated and characterized mouse photolyase-like genes, mCRY1 (mPHL L1) and mCRY2 (mPHLL2), which belong to the photolyase family includin g plant blue-light receptors, The mCRY1 and mCRY2 genes are located on chromosome 10C and 2E, respectively, and are expressed in all mouse o rgans examined, We raised antibodies specific against each gene produc t using its C-terminal sequence, which differs completely between the genes. Immunofluorescent staining of cultured mouse cells revealed tha t mCRY1 is localized in mitochondria whereas mCRY2 was found mainly in the nucleus, The subcellular distribution of CRY proteins was confirm ed by immunoblot analysis of fractionated mouse liver cell extracts, U sing green fluorescent protein fused peptides we showed that the C-ter minal region of the mouse CRY2 protein contains a unique nuclear local ization signal, which is absent in the CRY1 protein, The N-terminal re gion of CRY1 was shown to contain the mitochondrial transport signal, Recombinant as well as native CRY1 proteins from mouse and human cells showed a tight binding activity to DNA Sepharose, while CRY2 protein did not bind to DNA Sepharose at all under the same condition as CRY1, The different cellular localization and DNA binding properties of the mammalian photolyase homologs suggest that despite the similarity in the sequence the two proteins have distinct function(s).