TABLE 1. The V_max and K_m of glucose-6-phosphatase activity in crude microsomes and crude cytosol.

smlA⁻, Ax4 (WT), and countin⁻ cells were starved by shaking in PBM, harvested at 6 h of starvation, and lysed. Cell lysates were then clarified by centrifugation, and the clarified lysates were further fractionated by ultracentrifugation at 100,000 × g to yield crude microsomes and crude cytosol fractions. The glucose-6-phosphatase activities were normalized against the amount of protein present in cleared lysates. The V_max and K_m of glucose-6-phosphatase in cleared lysates were from Jang and Gomer (18), conservatively recalculating the countin⁻ K_m as <0.1 mm. For smlA⁻, wild-type, and countin⁻ cells, crude microsome protein was 37% of cleared lysate protein, and crude cytosol protein was 63% of cleared lysate protein.

Parameter measured	smlA −	Wild type	countin −
Vmax (crude microsomes)  (nmol/mg protein/min)	0.19	0.38	0.51
Km (crude microsomes) (mm)	0.40	0.65	<0.1
Vmax (crude cytosol)  (nmol/mg protein/min)	1.5	0.21	0.069
Km (crude cytosol) (mm)	1.2	0.18	<0.1
Vmax (cleared lysate)  (nmol/mg protein/min)	2.1	1.5	0.45
Km (cleared lysate) (mm)	2.4	2.1	<0.1