Document Detail


Cloning and functional characterization of squid voltage-dependent Ca2+ channel beta subunits: involvement of N-terminal sequences in differential modulation of the current.
MedLine Citation:
PMID:  12725917     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
cDNAs that encode beta subunits of voltage-dependent Ca(2+) channel were cloned from the optic lobe of the squid Loligo bleekeri. The subunits, LoCa(v)beta(1a) and LoCa(v)beta(1b) are 96% identical in amino acid sequence. The sole sequence differences are in the N-terminal region and in a five amino acid insertion in the central region of LoCa(v)beta(1b). RT-PCR revealed that LoCa(v)beta(1a) and LoCa(v)beta(1b) transcripts were expressed mainly in the optic lobe and stellate ganglion, and more weakly in mantle muscle, systemic heart, gill, branchial heart, stomach and liver. Coexpression of LoCa(v)beta(1a) or LoCa(v)beta(1b) with mammalian Ca(v)2.3 and alpha(2)/delta subunits in the Xenopus oocyte resulted in high-voltage-activated currents, and showed slow current inactivation and moderate steady-state inactivation. Comparison of the squid subunits with four mammalian beta subunits, beta(1b), beta(2a), beta(3) and beta(4), demonstrated that the modulatory effects of the beta subunits on steady-state inactivation kinetics were beta(3)<beta(4) approximately beta(1b)<LoCa(v)beta(1a) approximately LoCa(v)beta(1b)<beta(2a). LoCa(v)beta(1a)-induced current amplitude was about two to four times higher than that of LoCa(v)beta(1b). Experiments with point mutants and chimeras suggest that potential PKC and CK2 phosphorylation sites in the N-terminal region of LoCa(v)beta(1b) affect the current amplitude reciprocally, and may be responsible for regulating current amplitude.
Authors:
Tadashi Kimura; Tai Kubo
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Neuroscience research     Volume:  46     ISSN:  0168-0102     ISO Abbreviation:  Neurosci. Res.     Publication Date:  2003 May 
Date Detail:
Created Date:  2003-05-02     Completed Date:  2003-07-08     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  8500749     Medline TA:  Neurosci Res     Country:  Ireland    
Other Details:
Languages:  eng     Pagination:  105-17     Citation Subset:  IM    
Affiliation:
Molecular Neurophysiology Group, Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba Central 6, Tsukuba, Ibaraki 305-8566, Japan.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Sequence
Animals
Calcium Channels / chemistry*,  genetics,  metabolism*
Casein Kinase II
Chimera
Clone Cells
DNA, Complementary*
Decapodiformes / physiology*
Electric Stimulation
Electrophysiology
Membrane Potentials / physiology
Molecular Sequence Data
Mutation
Oocytes / metabolism
Optic Lobe, Nonmammalian / physiology*
Phosphorylation
Protein Kinase C / metabolism
Protein Subunits
Protein-Serine-Threonine Kinases / metabolism
Reverse Transcriptase Polymerase Chain Reaction
Sequence Homology, Amino Acid
Xenopus laevis
Chemical
Reg. No./Substance:
0/Calcium Channels; 0/DNA, Complementary; 0/Protein Subunits; EC 2.7.11.1/Casein Kinase II; EC 2.7.11.1/Protein-Serine-Threonine Kinases; EC 2.7.11.13/Protein Kinase C

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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