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Do voltage-gated calcium channel alpha2delta subunits require proteolytic processing into alpha2 and delta to be
L Douglas1, A Davies, J Wratten
1Department of Pharmacology, University College London, London WC1E 6BT, UK.
Biochemical Society Transactions
|October 21, 2006
Summary
Accessory alpha2delta-2 subunits of voltage-gated calcium channels are functional but rarely cleaved when expressed in cells, unlike their cerebellar counterparts. Future research will determine if cleaved or uncleaved forms are essential for calcium channel trafficking.
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- Accessory alpha2delta subunits are type 1 transmembrane proteins crucial for voltage-gated calcium channels.
- These subunits are highly glycosylated and contain disulfide bonds, influencing their structure and function.
- Skeletal-muscle alpha2delta-1 undergoes post-translational cleavage into alpha2 and delta subunits, which remain disulfide-bonded.
Purpose of the Study:
- To investigate the processing and cleavage of alpha2delta-2 subunits in various cell lines.
- To compare the processing of heterologously expressed alpha2delta-2 with endogenous alpha2delta-2 in the cerebellum.
- To assess the functional expression and plasma membrane localization of alpha2delta-2.
Main Methods:
- Stable and transient expression of alpha2delta-2 subunits in tsA-201, Cos-7, and NG108-15 cells.
- Comparison of subunit processing with endogenous alpha2delta-2 from cerebellar tissue.
- Assessment of protein functionality and plasma membrane localization.
Main Results:
- The vast majority of heterologously expressed alpha2delta-2 subunits were not cleaved into alpha(2)-2 and delta-2.
- Despite lack of cleavage, expressed alpha2delta-2 subunits demonstrated full functionality.
- Expressed alpha2delta-2 subunits were successfully localized to the plasma membrane.
Conclusions:
- Heterologous expression systems lead to differential processing of alpha2delta-2 subunits compared to endogenous cerebellar alpha2delta-2.
- The functional role of alpha2delta-2 in calcium channel trafficking may not strictly depend on its proteolytic cleavage.
- Further investigation is required to determine the functional significance of the cleaved versus uncleaved states of alpha2delta-2.
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