LRP130, a protein containing nine pentatricopeptide repeat motifs, interacts with a single-stranded cytosine-rich sequence of mouse hypervariable minisatellite Pc-1.

Recently, we have identified and purified minisatellite DNA binding proteins (MNBPs) that bind to the mouse hypervariable minisatellite Pc-1, from NIH3T3 cells. This study describes the isolation and characterization of a mouse leucine-rich protein (mLRP130) as one of the MNBPs that binds to the C-rich strand of Pc-1. The mLRP130 cDNA was demonstrated to encode a polypeptide of 1306 amino-acid residues with a deduced molecular mass of 137 kDa, and the mLRP130 mRNA is detected in various organs, including heart, brain, liver, skeletal muscle, kidneys and testes. The mLRP130 protein has nine copies of pentatricopeptide repeat (PPR) motifs that are considered to serve as protein-protein interactions. Two forms of the mLRP130 protein were detected in NIH3T3 cells with an approximate molecular mass of 140 kDa (mLRP130) and 100 kDa (mLRP130der), and were detected mainly in nuclear and cytoplasmic fractions, respectively. Immunofluorescence microscopic analysis demonstrated dominant localization of mLRP130 at the perinuclear region, and also in the nucleus and cytoplasm with dot- or squiggle-like staining. The immunoprecipitated mLRP130 bound to the single-stranded d(CTGCC)8, but not to its complementary G-rich strand of d(GGCAG)8 or double-stranded form. Possible biological roles of mLRP130 are discussed in association with the stability of minisatellite DNA sequences.