Complete complementary DNA-derived amino acid sequence of canine cardiac phospholamban.

Abstract

Complementary DNA (cDNA) clones specific for phospholamban of sarcoplasmic reticulum membranes have been isolated from a canine cardiac cDNA library. The amino acid sequence deduced from the cDNA sequence indicates that phospholamban consists of 52 amino acid residues ,and lacks an amino-terminal signal sequence. The protein has an. inferred mol wt 6,080 that is in agreement with its apparent monomeric mol wt 6,000, estimated previously by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Phospholamban contains two distinct domains, a hydrophilic region at the amino terminus (domain I) and a hydrophobic region at the carboxy terminus (domain II). We propose that domain I is localized at the cytoplasmic surface and offers phosphorylatable sites whereas domain II is anchored into the sarcoplasmic reticulum membrane.

Sarcolipin and phospholamban as regulators of cardiac sarcoplasmic reticulum Ca2+ ATPase

“…The inhibitory function of PLB is modulated by phosphorylation/ dephosphorylation and by an increase in intracellular Ca 2+ concentration [52][53][54]. Phospholamban can be phosphorylated at two distinct sites; -serine 16 by cAMP-dependent protein kinase (PKA), and threonine 17 by Ca 2+ -calmodulin-dependent protein kinase (CaMKII) during β-adrenergic stimulation [52,63,64]. Phosphorylation disrupts the physical interaction of PLB with SERCA2a and thus stimulates SR Ca 2+ transport by increasing the affinity of the SERCA2a for Ca 2+ , without a significant change in Vmax [51,[64][65][66][67][68][69].…”

“…Phospholamban can be phosphorylated at two distinct sites; -serine 16 by cAMP-dependent protein kinase (PKA), and threonine 17 by Ca 2+ -calmodulin-dependent protein kinase (CaMKII) during β-adrenergic stimulation [52,63,64]. Phosphorylation disrupts the physical interaction of PLB with SERCA2a and thus stimulates SR Ca 2+ transport by increasing the affinity of the SERCA2a for Ca 2+ , without a significant change in Vmax [51,[64][65][66][67][68][69]. This, in turn, leads to an increase in the velocity of relaxation, SR Ca 2+ load and, as a consequence, increased SR Ca 2+ release and myocardial contractility [51,70] Whereas de-phosphorylation of PLB by type 1 phosphatase (pp1) leads to the inhibition of the SERCA [71].…”

The cardiac sarcoplasmic reticulum phospholamban kinase is a distinct δ‐CaM kinase isozyme

“…The PLB-peptide, corresponding to amino acids 2-25 of PLB (cytoplasmic domain) according to the nomenclature given in [4,19] was synthesized by the solid phase method [20] and purified by reversephase HPLC on a Bischoft Polyencap 300 (10 mm particle size) column. The identity of the purified peptide was verified by amino acid analysis.…”

Rabbit cardiac and slow‐twitch muscle express the same phospholamban gene

“…2). The amino acid sequence corresponded to dog cardiac phospholamban with the exception that Asp2 in the dog protein [5] was replaced with Glu in the rabbit sequence. Dot matrix analysis of the rabbit cardiac muscle phospholamban and the longest dog cardiac muscle clone [12] indicated high nucleotide sequence identity, not only in the protein coding region (91Yo), but also in the 5'-and 3'-noncoding regions (not shown).…”

“…Dog cardiac phospholamban has been sequenced [3,4] and a cDNA has been cloned [5]. The presence of phospholamban in slow-twitch muscle has been inferred from phosphorylation patterns and immunological cross reactivity [6,7], but it is not known whether this protein is identical to cardiac phospholamban.…”