≥9,000 reactive subunits/cell
||Bacteria Escherichia coli
||Fox CF, Carter JR, Kennedy EP. Genetic control of the membrane protein component of the lactose transport system of Escherichia coli. Proc Natl Acad Sci U S A. 1967 Mar57(3):698-705. p.702 2nd paragraph & p.703 bottom paragraphPubMed ID16591520
||P.702 2nd paragraph: "Estimation of the minimum number of functional subunits of M protein per cell: On the assumption that a single cysteine residue is protected from attack by NEM [N-ethylmaleimide] when the M protein is complexed with TDG [thiodigalactoside], the minimum number per cell of functional subunits containing such a cysteine residue may be calculated."
||P.702 2nd paragraph: "Experiments in which the washing of the particulate fraction was avoided by the use of Sephadex G-25 to remove small molecules from the suspension, after treatment with unlabeled NEM in the presence of TDG, and in which the time of the incubation with labeled NEM was increased from 30 minutes to 60 minutes, indicated that the content of M protein is at least 9000 reactive subunits per cell, assuming that 1 mg of total cell protein represents approximately 3×10^9 cells." P.703 bottom paragraph: "Early estimates of the number of functional transport units suggested that this number might be in the range of 200-300/cell [refs 19, 20] but these estimates were necessarily indirect, and the authors clearly pointed out some of the assumptions needed for their calculations. More direct estimates reported here suggest that the number of functional subunits of M protein per cell in strain ML 308 is at least 9000. As
pointed out above, [investigators] assume in making this calculation that a single cysteine residue is protected from reaction with NEM when the protein is complexed with TDG."