The Conserved Box 1 Motif of Cytokine Receptors Is Required for Association with JAK Kinases

Abstract

The JAK2 tyrosine kinase is known to associate with the receptors for growth hormone (GH) and erythropoietin (EPO) and with the interleukin-6 receptor signal transducing protein, gp130. Here we demonstrate that chimeric cytokine receptors which contain the cytoplasmic domain of the receptors for GH and EPO or for gp130 can form complexes with JAK2 when transiently co-expressed in HeLa cells. Mutational analyses of chimeras for the the GH and EPO receptors and gp130 demonstrated that box 1, a motif critical for cytokine receptor signal transduction, was required for the association of JAK2. Although JAK2 was capable of associating with all three of the chimeras, JAK1 co-precipitated only with the gp130 chimera. Association of JAK1 and JAK2 with cytokine receptor proteins, therefore, requires the highly conserved box 1 domain, but other sequences within the receptor proteins may influence the specificity of JAK binding. Mutational analysis of JAK2 revealed that multiple or complex protein sequences within JAK2 are required for association with cytokine receptors.

Cloning of the human IL‐13Rα1 chain and reconstitution with the IL‐4Rα of a functional IL‐4/IL‐13 receptor complex

“…Since the cytoplasmic domain of IL-13Ral is 26 amino acids shorter than that of yc we are currently investigating whether IL-13Ral contributes to the recruitment of Jak3, as described for yc [23], and/ or to other signaling events as recently suggested [24]. In this context, it is important to emphasize the presence in the IL13Rod of a proline-rich motif located in the cytoplasmic region near the transmembrane domain suggesting that IL13Ral can associate with some kinases of the Jak family [25]. Together, these results show that IL-13Rod and IL4Roc are sufficient to reconstitute a functional receptor for IL-13 and IL-4, and they do not exclude the possibility that other protein(s) may be associated in some cell types with the natural IL-4/IL-13 receptor complex as recently described for yc [24,26].…”

Janus kinases: components of multiple signaling pathways

“…The Box 1 motif comprises of approximately eight prolinerich amino acids, that are required for interaction of several cytokine/growth factor receptors with JAK2. Thus, the Box 1 region of the receptors for prolactin, growth hormone, erythropoietin, IL-6 and related cytokines, that utilize the gp130 signal transducing receptor subunit, is required for association with JAK2 Miura et al, 1994;Tanner et al, 1995;Vanderkuur et al, 1994;Goujon et al, 1994;Hackett et al, 1995;DaSilva et al, 1994). Jiang et al (1996) used mutational analysis to demonstrate that the Box 1 region of cytokine receptors speci®es the region of interaction with JAK kinases.…”

Two Distinct Domains Within the N-Terminal Region of Janus Kinase 1 Interact with Cytokine Receptors

“…Box 1 is defined as a proline-rich motif (4), whereas box 2 is characterized as a cluster of hydrophobic amino acids (2). Most single subunit cytokine receptors, such as erythropoietin, growth hormone, and prolactin, as well as some heterodimeric receptors, such as IFN-␥ and GM-CSF/IL-3 and -5 interact with Jak2 through the highly conserved box 1 motif (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24).…”