Identification of an interferon-gamma receptor alpha chain sequence required for JAK-1 binding.
We have shown previously that a four-amino acid block residing at positions 266-269 (LPKS) in the intracellular domain of the human interferon-gamma (IFN-gamma) receptor alpha chain is critical for IFN-gamma-dependent tyrosine kinase activation and biologic response induction. Herein we show that this sequence is required for the constitutive attachment of the tyrosine kinase JAK-1. Using a vaccinia expression system, a receptor alpha chain-specific monoclonal antibody coprecipitated JAK-1 from cells coexpressing JAK-1 and either (a) wild type IFN-gamma receptor alpha chain, (b) a receptor alpha chain truncation mutant containing only the first 59 intracellular domain amino acids, or (c) a receptor mutant containing alanine substitutions for the functionally irrelevant residues 272-275. In contrast, JAK-1 was not coprecipitated when coexpressed with a receptor alpha chain mutant containing alanine substitutions for the functionally critical residues 266-269 (LPKS). Mutagenesis of the LPKS sequence revealed that Pro-267 is the only residue obligatorily required for receptor function. In addition, Pro-267 is required for JAK-1 binding. These results thus identify a site in the IFN-gamma receptor alpha chain required for constitutive JAK-1 association and establish that this association is critical for IFN-gamma signal transduction.
Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
D H
DH
Kaplan
A C
AC
Greenlund
J W
JW
Tanner
A S
AS
Shaw
R D
RD
Schreiber
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D053613:Janus Kinase 1; D051379:Mice; D008969:Molecular Sequence Data; D011392:Proline / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D017471:Receptors, Interferon / Q000737:chemistry / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D000096743:Interferon gamma Receptor
D015703:Antigens, CD; D053613:Janus Kinase 1; D011392:Proline; D011505:Protein-Tyrosine Kinases; D017471:Receptors, Interferon; D000096743:Interferon gamma Receptor; C507904:JAK1 protein, human; C507905:Jak1 protein, mouse