| First Author | Mita S | Year | 1993 |
| Journal | J Immunol | Volume | 151 |
| Issue | 12 | Pages | 6924-32 |
| PubMed ID | 8258700 | Mgi Jnum | J:16069 |
| Mgi Id | MGI:64163 | Doi | 10.4049/jimmunol.151.12.6924 |
| Citation | Mita S, et al. (1993) Comparative analysis of the kinetics of binding and internalization of IL-5 in murine IL-5 receptors of high and low affinity. J Immunol 151(12):6924-32 |
| abstractText | The high affinity IL-5R consists of at least two chains, alpha and beta. IL-5R alpha binds IL-5 with low affinity. IL-5R beta is required to construct the high affinity IL-5R, although IL-5R beta does not bind IL-5 by itself. To characterize the roles of IL-5R alpha and IL-5R beta on the association, dissociation, and internalization of IL-5, we compared the binding kinetics and the internalization of 35S-labeled IL-5 by high affinity IL-5R (dissociation constant approximately 150 pM) bearing T88-M with those by low affinity IL-5R (dissociation constant approximately 30 nM) bearing MOPC104E. We found that association kinetics of IL-5 to either natural receptor were similar. The maximal binding of IL-5 to both high and low affinity IL-5R was rapid (within 10 min). The dissociation of IL-5 from low affinity IL-5R was rapid (t1/2 < 30 min), but that from the high affinity IL-5R was remarkably slower (t1/2 > 120 min). The internalization of IL-5 was observed only in T88-M, but not in MOPC104E, suggesting that IL-5 internalization is mediated via high affinity IL-5R. Association and dissociation kinetics observed in natural cell line were mostly reproduced by the kinetic analysis of reconstituted IL-5R on transfectants with either the IL-5R alpha or the IL-5R alpha and IL-5R beta genes. However, transfectants that expressed IL-5R alpha significantly internalized IL-5, although the level was much lower than observed with IL-5R alpha beta transfectants. These results suggest that IL-5R alpha may be involved in the internalization of IL-5, whereas IL-5R beta is responsible for slowing the dissociation and the efficient internalization of IL-5 by stabilizing the ligand-receptor complex. |
