<modelParameter>Gpa1_num = </modelParameter>1434 to 4800 molecules/cell
- Quantitative western.
- Ghaemmaghami et al. (2003 PMID 14562106) measured 9920/cell by quantitative western of entire proteome.
- Yi et al. (2003 PMID 12960402) measured 10000/cell by quantitative western.
- Hao et al. (2003 PMID 12968019) measured ~8000/cell by quantitative western, and determined that only about 6000/cell are myristoylated.
- Thomson et al. (In preparation) measured 2390/cell by quantitative western.
Both Hao et al. and Thomson et al. made careful measurements using purified Gpa1 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.
Thus, we can only limit the total abundance of Gpa1 to lie between 2390 and 8000 molecules per cell
Gpa1 is myristoylated, and myristoylation is required for membrane localization of Gpa1 and mating pathway activity (Dohlman et al. 1993 PMID 8415763). Also, between 50% and 70% of Gpa1 is myristoylated in the absence of pheromone (Dohlman et al. 1993 PMID 8415763; Hao et al. 2003 PMID 12968019). We thus assume that only 60% of the total Gpa1 population can participate in the mating pathway. Thus, Gpa1_num = 0.6*(2390 to 8000 molecules/cell) = 1434 to 4800 molecule/cell.