AIC2A is a component of the purified high affinity mouse IL-3 receptor: temperature-dependent modulation of AIC2A structure.
IL-3, a potent hemopoietic growth factor, interacts with distinct classes of receptor, one of high affinity and the other of low affinity. The gene for a 115 kDa, low affinity IL-3 binding protein (AIC2A) was recently cloned. Ligand affinity purification was used to show that the AIC2A gene product participates in the formation of a high affinity IL-3 receptor (IL-3R). Cells were incubated with biotin-IL-3 at 4 degrees C and IL-3 bound to the low affinity site was removed by washing, cells were detergent extracted, and then streptavidin - agarose was used to purify proteins bound to biotin-IL-3. A 115 kDa phosphotyrosine (Ptyr)-containing protein was specifically purified and its identity as AIC2A was shown in Western assays using polyclonal anti-AIC2A antibodies. A brief temperature shift of the intact, biotin-IL-3-treated cells from 4 to 37 degrees C, prior to receptor purification, results in structural and compositional changes in the IL-3R, including: (i) a 10-20 kDa increase in the apparent Mr of both the AIC2A and the Ptyr antigens, and (ii) the association of a serine/threonine kinase. These observations indicate that in its native environment, the low affinity IL-3 binding protein, AIC2A, participates to form the high affinity IL-3R and is a substrate for a tyrosine kinase. Moreover, a ligand-induced, temperature-regulatable structural change in the IL-3R may be of importance in the transduction of information through the receptor, as suggested by the enhanced association of the IL-3R with a serine/threonine kinase.
Schreurs
J
J
Department of Molecular Biology, DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, CA 94304.
Hung
P
P
May
W S
WS
Arai
K
K
Miyajima
A
A
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000276:immunology; D008024:Ligands; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D016185:Receptors, Interleukin-3 / Q000737:chemistry* / Q000276:immunology; D013696:Temperature
D002352:Carrier Proteins; D008024:Ligands; D046911:Macromolecular Substances; D010455:Peptides; D010750:Phosphoproteins; D016185:Receptors, Interleukin-3; C072185:Csf2rb2 protein, mouse