Title : Role of glycosylation in cell surface expression and stability of
HERG potassium
channels
Abstract :
- The human ether-à-go-go-related gene ( HERG ) encodes the pore-forming subunit of the rapidly activating delayed rectifier potassium channel in the heart
- We previously showed that HERG channel protein is modified by N-linked glycosylation
- HERG protein sequence contains two extracellular consensus sites for N-linked glycosylation ( N598, N629 )
- In this study, we used the approaches of site-directed mutagenesis and biochemical modification to inhibit N-linked glycosylation and studied the role of glycosylation in the cell surface expression and turnover of HERG channels
- Our results show that N598 is the only site for N-linked glycosylation and that glycosylation is not required for the cell surface expression of functional HERG channels
- In contrast, N629 is not used for glycosylation, but mutation of this site (N629Q) causes a protein trafficking defect, which results in its intracellular retention
- Pulse-chase experiments show that the turnover rate of nonglycosylated HERG channel is faster than that of the glycosylated form, suggesting that N-linked glycosylation plays an important role in HERG channel stability