Cellular Accounting

Science's STKE  09 Jan 2007:
Vol. 2007, Issue 368, pp. tw16
DOI: 10.1126/stke.3682007tw16

Fluorescent labeling has allowed quantification of proteins in single cells, but potential problems arise from interference between reporter molecules themselves and interactions with other molecules within the cell. Huang et al. have devised a microfluidic chip for counting fluorescent proteins within a cell. Single cells are captured and lysed, and their contents are separated by electrophoresis and quantified by single-molecule fluorescence detection. This method was applied to natively fluorescent compounds (the phycobiliprotein subcomplexes in individual cyanobacterial cells grown under nitrogen-limited conditions), and proteins were labeled with fluorescent antibodies (β2 adrenergic receptor) present in low copy numbers.

B. Huang, H. Wu, D. Bhaya, A. Grossman, S. Granier, B. K. Kobilka, R. N. Zare, Counting low-copy number proteins in a single cell. Science 315, 81-84 (2007). [Abstract] [Full Text]