Catalytic Rate of transporter HXT7

Value 197 glucose molecules/sec
Organism Budding yeast Saccharomyces cerevisiae
Reference Ye L, Berden JA, van Dam K, Kruckeberg AL. Expression and activity of the Hxt7 high-affinity hexose transporter of Saccharomyces cerevisiae. Yeast. 2001 Sep 30 18(13):1257-67. p.1265 left column 2nd paragraphPubMed ID11561293
Method "Glucose uptake was assayed as described (Walsh et al., 1994) at five concentrations of D-U- (14C)-glucose [1, 2.5, 5, 10 and 25 mM (371, 297, 148, 74 and 30 MBq/mol, respectively)]. The data were fit to the Michaelis–Menten equation using ENZFITTER software (Elsevier-Biosoft). Total cell protein was measured by the method of Lowry (Lowry et al., 1951) using a COBAS Auto-analyzer (Roche) after digestion of cells overnight in 1 N NaOH. Bovine serum albumin was used as a standard. Cell number was determined by counting at least 1000 cells with a haemocytometer."
Comments "The cellular abundance of the Hxt7::GFP chimera and the glucose transport activity mediated by that protein were used to calculate the catalytic centre activity of Hxt7 for glucose. For the first time point (mid-exponential phase), the Hxt7::GFP cell suspension contained 0.61 mg total cell protein/ ml, giving a relationship of 4.5 pmol Hxt7::GFP/mg total cell protein. The Vmax for glucose transport of these cells, 53 nM/min/mg total cell protein, was divided by this value, resulting in an estimate of 197/s for the catalytic-centre activity of Hxt7::GFP." See BNID 101737, 101738
Entered by Ben Marks
ID 101737