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Sarcolipin bioactive peptide and similar proteins Vertebrate sarcolipin (SLN) belongs to a family of bioactive peptides which includes phospholamban (PLN), and invertebrate sarcolamban (SCL). SCLA and SCLB are encoded within a single putative noncoding transcript, pncr003:2L; PLN and SLN are each encoded within a single exon of a spliced transcript. PLN is chiefly expressed in the cardiac muscle, while SLN is expressed in the atria of the heart and embryonic slow-type skeletal muscle; SCL is found in cardiac and somatic muscle of Drosophila melanogaster. PLN and SLN are each a single-pass transmembrane alpha-helix that interacts directly with the sarcoplasmic reticulum (SR) calcium pump (SERCA), lower its affinity for Ca2+, thereby decreasing the rate of Ca2+ reuptake into the SR from the sarcoplasm. In the heart, PLN and SLN inhibit the activity of SERCA2a isoform and function as important regulators of cardiac contractibility and disease. SCLA and SCLB are each predicted to form a single-pass transmembrane helix, localize to the SR with the SR calcium pump (Ca-P60A), and dampen its activity. PLN and SLN differ in their interaction with SERCA. SLN in skeletal muscle has also been shown to amplify calcineurin signaling, and is a potential therapeutic target for the management of muscular dystrophy, as it is upregulated in the skeletal muscle of the classical mouse model for Duchenne muscular dystrophy. |
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