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			PubMed Journals: J Biol Chem

  Source:		PMID: 6333425


    		J Biol Chem. 1984 Nov 10;259(21):13504-10.
     
			HLA-A2 antigen phosphorylation in vitro by
			cyclic AMP-dependent protein kinase. Sites
			of phosphorylation and segmentation in class
			i major histocompatibility complex gene
			structure.

			Guild BC, Strominger JL.

			The heavy chain of the HLA-A2 antigen is
			phosphorylated by cyclic AMP-dependent protein
			kinase at two serine residues of the intracellular
			region. Limited proteolysis was performed
			on purified [32P]HLA-A2 antigens in order
			to define the sites of phosphorylation.
			Both of the phosphorylated serine residues
			are located in the carboxyl terminus of
			the heavy chain; one is encoded by exon
			5, while the other is encoded by exon 6.
			The phosphoserine encoded by exon 5 is part
			of the conserved sequence Arg-Arg-Lys-Ser-Ser.
			This protein sequence contains the proper
			arrangement of amino acids for recognition
			and phosphorylation by the catalytic subunit
			of cyclic AMP-dependent protein kinase.
			In the murine class I antigens (H-2), exon
			5 encodes a similar sequence of basic residues
			followed by one intervening residue and
			a threonine rather than a serine residue
			in the last amino acid position. A composite
			figure is presented that compares the
			carboxyl-terminal sequences of human and
			murine class I antigens and illustrates
			the known sites of phosphorylation recognized
			by various kinases. Each site of phosphorylation
			in the carboxyl terminus is contained within
			a conserved protein sequence encoded by
			one of the three exons. A separation and
			preservation of unique sites of phosphorylation
			could explain why there is segmentation
			in the genomic arrangement of class I molecules.

			PMID: 6333425 [Indexed for MEDLINE]

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