TY - JOUR
T1 - Differential phosphorylation of two size forms of the neuronal class C L-type calcium channel α1 subunit
AU - Hell, Johannes W.
AU - Yokoyama, Charles T.
AU - Wong, Scott T.
AU - Warner, Concepcion
AU - Snutch, Terry P.
AU - Catterall, William A.
PY - 1993/9/15
Y1 - 1993/9/15
N2 - L-type calcium channels mediate long-lasting calcium currents which are modulated by protein phosphorylation. Using site-directed anti-peptide antibodies, we show that the al subunit of the neuronal class C L-type calcium channel from rat brain exists in two size forms. The longer form, LC2, with an apparent molecular mass of 210-235 kDa was phosphorylated in vitro by cAMP-dependent'protein kinase (cA-PK), but the shorter form, LC1, with an apparent molecular mass of 190-195 kDa was not a substrate for cA-PK. In contrast, LC1 and LC2 are both substrates for protein kinase C (PKC), calcium- and calmodulin-dependent protein kinase II, and cGMP-dependent protein kinase (cG-PK). The site-directed anti-peptide antibody CNC2 was produced against the COOH-terminal end of the class C L-type α1 subunit as predicted by molecular cloning and sequencing of cDNA. CNC2 recognized LC2 but not LC1 by immunoblotting and immunoprecipitated only LC2 phosphorylated by either cA-PK or PKC. These results indicate that LC1 is truncated at its COOH-terminal end with respect to LC2 and that cA-PK preferentially phosphorylates sites in the COOH-terminal region of the al subunit that are present in Lc2 but not LC1. The selectivity of cA-PK for phosphorylation of the COOH-terminal region of LC2 suggests that the channel activities of the two α1 subunit size forms may be differentially regulated by neurotransmitters and hormones which act through cAMP-dependent mechanisms, while both α1 subunit isoforms may be modulated by PKC, cG-PK, and calcium- and calmodulin-dependent protein kinase II.
AB - L-type calcium channels mediate long-lasting calcium currents which are modulated by protein phosphorylation. Using site-directed anti-peptide antibodies, we show that the al subunit of the neuronal class C L-type calcium channel from rat brain exists in two size forms. The longer form, LC2, with an apparent molecular mass of 210-235 kDa was phosphorylated in vitro by cAMP-dependent'protein kinase (cA-PK), but the shorter form, LC1, with an apparent molecular mass of 190-195 kDa was not a substrate for cA-PK. In contrast, LC1 and LC2 are both substrates for protein kinase C (PKC), calcium- and calmodulin-dependent protein kinase II, and cGMP-dependent protein kinase (cG-PK). The site-directed anti-peptide antibody CNC2 was produced against the COOH-terminal end of the class C L-type α1 subunit as predicted by molecular cloning and sequencing of cDNA. CNC2 recognized LC2 but not LC1 by immunoblotting and immunoprecipitated only LC2 phosphorylated by either cA-PK or PKC. These results indicate that LC1 is truncated at its COOH-terminal end with respect to LC2 and that cA-PK preferentially phosphorylates sites in the COOH-terminal region of the al subunit that are present in Lc2 but not LC1. The selectivity of cA-PK for phosphorylation of the COOH-terminal region of LC2 suggests that the channel activities of the two α1 subunit size forms may be differentially regulated by neurotransmitters and hormones which act through cAMP-dependent mechanisms, while both α1 subunit isoforms may be modulated by PKC, cG-PK, and calcium- and calmodulin-dependent protein kinase II.
UR - http://www.scopus.com/inward/record.url?scp=0027198392&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0027198392&partnerID=8YFLogxK
M3 - Article
C2 - 8396138
AN - SCOPUS:0027198392
SN - 0021-9258
VL - 268
SP - 19451
EP - 19457
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 26
ER -