In this article we will discuss about the structure of cytokines with its suitable diagram.
1. Cytokines are proteins or glycoproteins which normally have a molecular mass of less than 30 KDa.
2. Structural predictions suggest that cytokines belong to haematopoietins, included in the haematopoietin family of interleukins (2-7, 9, 11-13 and 15) GM-CSF, G-GSF, leukomia- inhibitory factor (LIF) and ciliary neurotrophic factor (CNTF) [confirmed by X-ray crystallographic sequence analysis].
3. The amino acid sequences of the various haematopoietins differ accordingly—all of them have a high-degree of α-helical structure and little or no β-sheet structure.
4. The structure of haematopoietin IL-2 is mentioned in the Fig. 8.5.
Cytokine Homologues:
Several virus encode cytokine homologues:
1. Human herpes virus: which causes Kaposi’s sarcoma, normally encode a homologue of human IL-6. It induces cell proliferation and is more efficient in signal transduction than IL-6.
2. Human herpes virus: also induces the secretion of a homologue of the chemokine MIP-2, a broad-spectrum chemokine antagonist.
3. IL-10 homologues (VIL-10) are encoded by several other herpes virus such as the Epstein-Barr virus and cytomegalovirus. VIL-10 mimics the immunosuppressive and anti-inflammatory activities of host IL-10 but lacks its immunostimulatory properties. Like IL-10, VIL-10 can also induce proliferation, increasing the target cell pool for the virus.