Title : Functional analysis of site-directed glycosylation mutants of the human
equilibrative nucleoside transporter-2
Abstract :
- Protein glycosylation is important for nucleoside transport, and this has been demonstrated for the human equilibrative nucleoside transporter-1 ( hENT1 )
- It is not known whether glycosylation affects the functions of hENT2 or where hENT2 is glycosylated
- We address these questions using N-glycosylation mutants (N48D, N57D, and N48/57D) and demonstrate that hENT2 is glycosylated at Asn(48) and Asn(57)
- Our results show that although the apparent affinities for [3H]uridine and [3H]cytidine of the mutants were indistinguishable from those of the wild-type protein , N-glycosylation was required for efficient targeting of hENT2 to the plasma membrane
- All mutants had a two- to threefold increase in IC(50) for dipyridamole
- N57D and N48/57D, but not N48D, also had a twofold increase in IC(50) for NBMPR
- We conclude that the relative insensitivity of hENT2 to inhibitors is primarily due to its primary structure and not to glycosylation
- Glycosylation modulates hENT1 function, but is not required for hENT2
Output (sent_index, trigger,
protein,
sugar,
site):
- 2. glycosylated, , hENT2, -, -
- 2. glycosylation, , hENT2, -, -
- 3. glycosylated, , -, -, Asn(48) and Asn(57)
- 3. glycosylated, , hENT2, -, Asn(48) and Asn(57)
- 4. N-glycosylation, , hENT2, -, -
Output(Part-Of) (sent_index,
protein,
site):
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):
- 3. hENT2, -, Asn(48) and Asn(57)