IL-1 alpha

IL1α and IL1β are both synthesized as 31 kDa precursors that are subsequently cleaved into proteins with molecular weights of approximately 17,000 Da. Neither precursor contains a typical hydrophobic signal peptide sequence and most of the precursor form of IL1α remains in the cytosol of cells, although there is evidence for a membranebound form of the precursor form of IL1α. The IL1α precursor reportedly shows full biological activity in the EL4 assay. Among various species, the amino acid sequence of mature IL 1α is conserved 60% to 70% and human IL1 has been found to be biologically active on murine cell lines. Both forms of IL1 bind to the same receptors, designated type I and type II. Evidence suggests that only the type I receptor is capable of signal transduction and that the type II receptor may function as a decoy, binding IL1 and thus preventing binding of IL1 to the type I receptor.