MOLECULAR-MODEL OF AN ALTERNATIVE SPLICE VARIANT OF HUMAN IL-4, IL-4-DELTA-2, A NATURALLY-OCCURRING INHIBITOR OF IL-4-STIMULATED T-CELL PROLIFERATION

The molecular model of IL-4 delta 2, a naturally occurring splice vari ant of human IL-4 with exons 1, 3, and 4 in an open reading frame, is described. The second exon codes the main part of the long loop AB con nected the helices A and B in parallel superposition. Therefore the hy drophobic core and the native fold of the rest part of IL-4 delta 2 mo lecule could be preserved without any significant changes only in the case of revolution of the helix A relative to other helices. In the re sult, the dominated a left-handed four-helix bundle structure of IL-4 with an up-up-down-down structural pattern is transformed to the IL-4 delta 2 structure with a down-up-down-down structural pattern. (C) 199 7 Elsevier Science B.V.