This family, interleukin 23 subunit alpha, is a heterodimer consisting of a 40 kDa subunit - p40 - that is shared with IL12 and a unique 19 kDa subunit - p19. IL23 is a pro-inflammatory cytokine that binds to adnectins and thus plays a key role in the pathogenesis of several autoimmune and inflammatory diseases. IL23 signalling on the cell membrane works through the interaction of four proteins, two of which are shared with the IL12-receptor complex; signalling through the cell membrane involves the combined aggregation of at least two receptor components and then the subsequent activation of the Jak/Tyk tyrosine kinases and the family of STAT transcription factors [1,2,3].

1: The structure of interleukin-23 reveals the molecular basis of p40 subunit sharing with interleukin-12. Lupardus PJ, Garcia KC; J Mol Biol. 2008;382:931-941. PMID:18680750

2: Crystal structures of the pro-inflammatory cytokine interleukin-23 and its complex with a high-affinity neutralizing antibody. Beyer BM, Ingram R, Ramanathan L, Reichert P, Le HV, Madison V, Orth P; J Mol Biol. 2008;382:942-955. PMID:18708069

3: Structures of adnectin/protein complexes reveal an expanded binding footprint. Ramamurthy V, Krystek SR Jr, Bush A, Wei A, Emanuel SL, Das Gupta R, Janjua A, Cheng L, Murdock M, Abramczyk B, Cohen D, Lin Z, Morin P, Davis JH, Dabritz M, McLaughlin DC, Russo KA, Chao G, Wright MC, Jenny VA, Engle LJ, Furfine E, Sheriff S; Structure. 2012;20:259-269. PMID:22325775