Cloning of rat "prion-related protein" cDNA

Rat prion-related protein (PrP) cDNA has been cloned and sequenced. Comparison of this cDNA with those from human, hamster, and mouse indicates extremely high conservation (about 95%). The deduced partial rat PrP possesses: (a) a highly conserved region composed of repetitive sequences in what is presumably an extracellular domain, (b) a hydrophobic transmembrane domain, (c) a highly charged region which should stop membrane transfer, (d) a substantial cytoplasmic domain (which contains all of the nonconservative substitutions and a high proportion of conservative substitutions), and (e) a hydrophobic C-terminus. Dot and Northern blot analyses suggest a limited expression of PrP in rat tissues and indicate that PrP expression is decreased in the brain during the acute phase response systemically. Our results lend support to the notion that PrP is a highly conserved, normal cellular membrane protein of essential (although unknown) biologic function, which may be deposited in fibrillar amyloid form as a result of abnormal processing.