School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast, BT9 7BL, UK.
Mol Cell Biochem. 2012 Dec;371(1-2):217-23. doi: 10.1007/s11010-012-1438-0. Epub 2012 Sep 4.
IQGAPs are cytoskeletal scaffolding proteins which collect information from a variety of signalling pathways and pass it on to the microfilaments and microtubules. There is a well-characterised interaction between IQGAP and calmodulin through a series of IQ-motifs towards the middle of the primary sequence. However, it has been shown previously that the calponin homology domain (CHD), located at the N-terminus of the protein, can also interact weakly with calmodulin. Using a recombinant fragment of human IQGAP1 which encompasses the CHD, we have demonstrated that the CHD undergoes a calcium ion-dependent interaction with calmodulin. The CHD can also displace the hydrophobic fluorescent probe 1-anilinonaphthalene-8-sulphonate from calcium-calmodulin, suggesting that the interaction involves non-polar residues on the surface of calmodulin. Molecular modelling identified a possible site on the CHD for calmodulin interaction. The physiological significance of this interaction remains to be discovered.
IQGAPs 是细胞骨架支架蛋白，可从多种信号通路收集信息，并将其传递到微丝和微管。在一级序列的中间有一系列 IQ 基序，IQGAP 与钙调蛋白之间存在明确的相互作用。然而，先前已经表明，位于蛋白质 N 端的钙调蛋白同源结构域 (CHD) 也可以与钙调蛋白弱相互作用。使用包含 CHD 的人 IQGAP1 的重组片段，我们已经证明 CHD 与钙调蛋白发生钙离子依赖性相互作用。CHD 还可以使疏水性荧光探针 1-苯胺基萘-8-磺酸盐从钙-钙调蛋白中置换出来，表明该相互作用涉及钙调蛋白表面的非极性残基。分子建模确定了 CHD 上钙调蛋白相互作用的可能位点。这种相互作用的生理意义尚待发现。
