PubMed Journals: Biochim Biophys Acta
Source: PMID: 8664319
⇦ ⇨ Biochim Biophys Acta. 1996 Jun 11;1281(2):205-12.
Cyclic AMP-dependent protein kinase phosphorylates
residues in the C-terminal domain of the cardiac
L-type calcium channel alpha1 subunit.
Leach RN(1), Brickley K, Norman RI.
(1) Department of Medicine and Therapeutics,
University of Leicester, Clinical Sciences
Building, Leicester Royal Infirmary, UK.
The molecular basis of the regulation of
cardiac L-type calcium channel activity
by cAMP-dependent protein kinase (cA-PK)
remains unclear. Direct cA-PK-dependent
phosphorylation of the bovine ventricular
alpha1 subunit in vitro has been demonstrated
in microsomal membranes, detergent extracts
and partially purified (+)-[3H]PN 200-110
receptor preparations. Two 32P-labeled
phosphopeptides, derived from cyanogen bromide
cleavage, of 4.7 and 9.5 kDa were immunoprecipitated
specifically by site-directed antibodies
against the rabbit cardiac alpha1 subunit
amino acid sequences 1602-1616 and 1681-1694,
respectively, consistent with phosphorylation
at the cA-PK consensus sites at Ser(1627)
and Ser(1700). No phosphopeptide products
consistent with phosphorylation at three
other C-terminal cA-PK consensus phosphorylation
sites (Ser(1575), Ser(1848) and Ser(1928))
were identified using similar procedures
suggesting that these sites are poor substrates
for this kinase. Ser(1627) and Ser(1700)
may represent sites of cA-PK phosphorylation
involved in the physiological regulation of cardiac
L-type calcium channel function.
PMID: 8664319 [Indexed for MEDLINE]