Interleukin 27 alpha subunit (IL27,IL27A, IL27p28) and Cytokine like factor 1 (CRLF1) form a secreted complex. Secretion of IL27 was observed in HEK 293 cells transfected with IL27 cDNA in the absence of CRLF1. This may indicate that formation of a complex is not strictly required for IL27 secretion in these cells. Alternatively it could reflect the formation of a complex between IL27 and endogenous CRLF1, which is expressed in HEK 293 cells. The IL27:CRLF1 complex is biologically active (Crabé et al. 2009).
This reaction is a black box event because the mechanism of translocation is unknown.