Nucleotide sequence of a dog class I cDNA clone

Abstract

In the rat major histocompatibility complex (MHC), six class I loci (A, Pa, F, E, G, and C) have been detected serologically or have been identified and mapped by DNA hybridization (Gill et al. 1987, Cortese Hassett et al. 1986). However, the complete structure of a rat class I MHC gene is not yet known. Only two partial rat cDNA class I clones have been sequenced (Kastern 1985), and they contain only the coding region for the third extracellular domain or for the transmembrane-cytoplasmic region and 3' untranslated end. In this paper, we report the DNA sequence of a 1.6 kb clone from a rat placental cDNA library made from (WF × DA)F 1 placentas. The amino acid sequence deduced from the clone is quite similar to the o~1, c~2, a3, and transmembranecytoplasmic domains of the class I transplantation antigens from other species, but it has some unique features. The cDNA library was made using a modification of the method of Gubler and Hoffman (1983) from mRNA of 18-day-old ( W F × D A ) F 1 (u×a) placentas. The cDNA was ligated to Protoclone kgtl 1 DNA (Promega, Biotec, Madison, Wisconsin) (Huynh et al. 1985), and the library was screened by hybridization analysis with the mouse class I cDNA probe pAG64c. Class I-specific clones were identified, purified, and mapped with restriction enzymes. The longer clones (ca 1.5 kb) were subcloned into the Eco RI site of Bluescript KS + (Stratagene San Diego, California), and several of them were sequenced both by the chemical degradation method (Maxam and Gilbert 1980) and by the chain termination method (Sanger et al. 1977) using Sequenase (USB, Cleveland, Ohio). The clone pARI.5, which is 1.6 kb long, contains an entire class I transcript, and it was the most abundant type of class I clone in the placental library as determined by restriction enzyme mapping. This clone was doubly sequenced from overlapping restriction enzyme fragments generated by using the enzymes Sst I, Sst II, Pst I, Pvu II, and Hinc II (BRL, Gaithersburg, Maryland).