SEQUENCE-ANALYSIS OF PG10.2, A GENE EXPRESSED IN THE PINEAL-GLAND ANDTHE OUTER NUCLEAR LAYER OF THE RETINA

A cDNA (PG10.2) was cloned from rat using RNA fingerprinting by arbitr arily primed PCR (AP-PCR). Initially, a 145-bp DNA fragment was isolat ed from a pineal-specific band revealed on a sequencing gel. Riboprobe s generated from the DNA fragment were used for hybridization histoche mical and Northern analyses. Both techniques indicate a gene (8 kb mRN A) expressed only in the pineal gland and the outer nuclear layer of t he retina. Two 4-kb cDNA fragments generated by 5'-RACE (rapid amplifi cation of cDNA ends) and 3'-RACE were obtained using a long template P CR-based RACE technique. DNA sequencing revealed a single long open re ading frame (ORF) encoding a predicted protein of 1239 amino acids, co ntaining multiple motifs: a typical signal sequence of 20 amino acids at the NH2-terminus, a long extracellular domain with multiple potenti al glycosylation sites, a 31-amino-acid transmembrane domain near the COOH-terminus and a 109-amino-acid cytoplasmic tail. There are also tw o domains similar, but not identical, to EGF-like (epidermal growth fa ctor-like) domains located just upstream of the transmembrane domain. These features suggest that this gene may encode a glycoprotein involv ed in cell adhesion, growth, and differentiation of pineal and retinal photoreceptor cells.