Functional cardiac L-type @entity460 channels are composed of the pore-forming alpha(1C) subunit and the regulatory @entity8042 and alpha(2)/delta subunits. To investigate possible developmental changes in @entity460 channel composition, we examined the temporal expression pattern of alpha(1C) and @entity8042 subunits during cardiac ontogeny in @entity19 and @entity35 , using sequence-specific antibodies. Fetal and neonatal hearts showed two size forms of alpha(1C) with 250 and 220 kDa. Quantitative immunoblotting revealed that the @entity35 cardiac 250-kDa alpha(1C) subunit increased about 10-fold from fetal days 12-20 and declined during postnatal maturation, while the 220-kDa alpha(1C) decreased to undetectable levels. The expression profile of the 85-kDa @entity8042 subunit was completely different: @entity8042 was not detected at fetal day 12, rose in the neonatal stage, and persisted during maturation. Additional @entity8042 -stained bands of 100 and 90 kDa were detected in fetal and newborn hearts, suggesting the transient expression of @entity8042 subunit variants. Furthermore, two fetal proteins with beta(4) immunoreactivity were identified in @entity35 hearts that declined during prenatal development. In the fetal @entity35 heart, beta(4) gene expression was confirmed by RT-PCR. Cardiac and brain beta(4) mRNA shared the 3 prime region, predicting identical primary sequences between @entity535 residues 62-519, diverging however, at the 5 prime portion. The data indicate differential developmental changes in the expression of @entity141 channel subunits and suggest a role of fetal alpha(1C) and beta isoforms in the assembly of @entity141 channels in immature cardiomyocytes.

Expression of @entity141 channel subunits during cardiac ontogeny in @entity19 and XXXX : identification of fetal alpha(1C) and beta subunit isoforms.

@entity8042 :: ('15130(Tax:10090)', 'Gene') :: ['beta(2)'] @entity19 :: ('10090', 'Species') :: ['mice'] @entity535 :: ('CHEBI:33704', 'Chemical') :: ['amino acid'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca(2+)'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium'] @entity35 :: ('10116', 'Species') :: ['rat', 'rats']
@entity35 :: (10116,Species) :: ['rats']
