CASPARI, T and STADLER, R and SAUER, N and TANNER, W (1994) STRUCTURE-FUNCTION RELATIONSHIP OF THE CHLORELLA GLUCOSE/H+ SYMPORTER. JOURNAL OF BIOLOGICAL CHEMISTRY, 269 (5). pp. 3498-3502. ISSN 0021-9258,
Full text not available from this repository.Abstract
The Clorella kessleri HUP1 gene coding for a hexose/H+ symporter has been expressed in a glucose uptake-deficient mutant of Schizosaccharomyces pombe. The transformants are able to grow on glucose and to accumulate 3-O-methylglucose 100-fold. This system has been used to test the activity of specifically mutated HUP1 cDNAs. All three histidyl residues were exchanged with arginine (H73R, H170R, and H495R) without a major effect on transport activity. When Asp-44 within the first transmembrane helix was replaced by Asn, the transporter was inactive; replacement by Glu (D44E) resulted in a loss of activity by 90% and a 15-fold increased K(m) value. Glutamine residues conserved in all glucose transporters sequenced so far were exchanged: Q179N (in helix 5), Q298G and Q299N (both in helix 7). Whereas Q298G only resulted in a small K(m) change, both Q179N and Q299N showed an increase in K(m) by a factor of 10. Inserting 4 additional amino acids each into the two largest loops (1 and 6) reduced the activity dramatically; only in the latter case this was due to decreased protein synthesis or stability. Two COOH-terminal deletions (-27 and -43 amino acids) were also tested. The 27 COOH-terminal amino acids, but not the 43 COOH-terminal amino acids, could be removed without affecting transporter activity.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | TRANSPORT ACTIVITY; LACTOSE PERMEASE; EXPRESSION; SEQUENCE; CLONING; PROTEIN; GENE; TRYPTOPHAN-412; CARRIER; INVIVO; |
| Depositing User: | Dr. Gernot Deinzer |
| Last Modified: | 19 Oct 2022 08:40 |
| URI: | https://pred.uni-regensburg.de/id/eprint/53464 |
Actions (login required)
 |
View Item |
