| Range |
459-742 sec^-1
|
| Organism |
Chinese hamster |
| Reference |
Cavet ME, Akhter S, de Medina FS, Donowitz M, Tse CM. Na(+)/H(+) exchangers (NHE1-3) have similar turnover numbers but different percentages on the cell surface. Am J Physiol. 1999 Dec277(6 Pt 1):C1111-21. p. C1119 Table 2 Table - link PubMed ID10600762
|
| Method |
A Chinese hamster lung fibroblast cell line (PS120) previously
selected to lack all endogenous NHEs was stably
transfected, using Lipofectin (GIBCO BRL), with human
NHE1 or rabbit NHE2 or NHE3 cDNAs epitope tagged on the
COOH termini with a previously described 11-amino acid
epitope of vesicular stomatitis virus glycoprotein (VSVG) plus
an 8-amino acid spacer (NHE1V, NHE2V, and NHE3V). Researchers then determined the turnover
numbers of NHE1, NHE2, and NHE3 expressed in the
same cell type (PS120) by correlating the Vmax (as
measured by 22Na+ uptake kinetic studies and fluorometry)
with the amount of NHE protein expressed at the
cell surface. |
| Comments |
In the present study, all three NHE isoforms had a turnover rate of ~80–100 s^-1 when Na+ uptake was used to measure Vmax at 22°C (BNID 105479) and a turnover number of 459–742 s^-1 when fluorometry at 37°C was used. NHEs in lymphocytes (likely to be NHE1) have a high temperature coefficient (Q10) of 3.1 (Livne et al 1987, PMID 2832967). When this is taken into account, the estimated turnover number for NHE1 determined by fluorometry at 22°C is 142 s^-1, which is close to that measured by 22Na+ uptake (80 s^-1). |
| Entered by |
Uri M |
| ID |
105481 |