Crystallization of PINCH LIM1/ILK1 ankyrin domain complex and CD40 receptor

Abstract

ILK1 (integrin-linked kinase 1), serine/threonine-protein kinase, regulates cell adhesion, and growth factor signaling pathways. And PINCH (particularly interesting new cys-his protein) is adaptor protein of ILK1, contributing focal adhesions. ILK1 interacts with cytoplasmic domain of beta-integrin, physically links integrin to actin cytoskeleton, and also transduces integrin signals to actin. To do these functions of ILK1, ILK1 should form a complex with PINCH. Many biochemical, cell biological, and genetical experiments have reported that PINCH and ILK1 form a complex with binding between PINCH LIM1 domain and ILK1 ankyrin repeats domain. To fully understand the integrin signaling pathway through ILK1, the molecular structural changes when ILK1 and PINCH form and dissociate a complex should be studied. In this paper, the crystal of PINCH LIM1 and ILK1 ankyrin repeats complex was obtained. As a future work, X-ray crystal structure of this complex could be solved after improvement of these crystals. CD40 receptor, CD40, is tumor necrosis factor receptor superfamily member 5. CD40 is transmembrane protein, which is located in plasma membrane of B-cell. Three CD40s bind to trimer CD40 ligand as a trimer, and this complex transduces various signals with downstream regulator, TRAF (tumour necrosis factor receptor associated factor). So understanding the structural conformation of CD40-CD40L complex, the upstream regulator on immune response, is important. In this paper, the extracellular domain of CD40 receptor was crystallized, and this crystal has improved amazingly. Also, it was confirmed that this crystal could diffract X-ray.