<modelParameter>Ste4_num = 818</modelParameter> molecules/cell
- Quantitative western.
- Ghaemmaghami et al. (2003 PMID 14562106) measured 2050/cell by quantitative western of entire proteome.
- Yi et al. (2003 PMID 12960402) measured 10000/cell by quantitative western.
- Thomson et al. (In preparation) measured 2045/cell by quantitative western.
Thomson et al. made careful measurements using purified Ste4 as a protein standard for their Western blots. Ghaemmaghami et al. used a common protein standard for all proteins measured, and Yi et al. did not explain how they made their measurements. Because of they accounted for more sources of error, we trust the abundance measured by Thomson et al., 2045 molecules/cell.
Only about 40% of the total cellular pool of Ste4 is associated with the plasma membrane(Hirschman et al. 1997 PMID 8995254). Although cytoplasmic Ste4 is able to interact with Gpa1, it is unable to support mating signal in the presence of pheromone(Manahan et al. 2000 PMID 10712512). Thus, we consider only the fraction of the cellular Ste4 pool that is associated with the plasma membrane: Ste4_num = 0.4*2045 molecules/cell = 818 molecules/cell.