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
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]