Label-free detection of protein-protein interactions using a calmodulin-modified nanowire transistor.
In this study, we describe a highly sensitive and reusable silicon nanowire field-effect transistor for the detection of protein-protein interactions. This reusable device was made possible by the reversible association of glutathione S-transferase-tagged calmodulin with a glutathione modified transistor. The calmodulin-modified transistor exhibited selective electrical responses to Ca2+ (> or = 1 microM) and purified cardiac troponin I (approximately 7 nM); the change in conductivity displayed a linear dependence on the concentration of troponin I in a range from 10 nM to 1 microM. These results are consistent with the previously reported concentration range in which the dissociation constant for the troponin I-calmodulin complex was determined. The minimum concentration of Ca2+ required to activate calmodulin was determined to be 1 microM. We have also successfully demonstrated that the N-type Ca2+ channels, expressed by cultured 293T cells, can be recognized specifically by the calmodulin-modified nanowire transistor. This sensitive nanowire transistor can serve as a high-throughput biosensor and can also substitute for immunoprecipitation methods used in the identification of interacting proteins.
Lin
Tsung-Wu
TW
Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 106, Taiwan.
Hsieh
Po-Jen
PJ
Lin
Chih-Lung
CL
Fang
Yi-Ya
YY
Yang
Jia-Xun
JX
Tsai
Chia-Chang
CC
Chiang
Pei-Ling
PL
Pan
Chien-Yuan
CY
Chen
Yit-Tsong
YT
D002147:Calmodulin / Q000378:metabolism*; D053770:Nanowires; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*
D002147:Calmodulin; D011506:Proteins