SR proteins and PLN expression levels in explanted heart tissue of proband III-4 in kindred I. (a) Quantitative immunoblotting of PLN, SERCA2a, and calsequestrin in explanted heart tissue of homozygous proband III-4, a nonfamilial heart failure patient, and a normal donor subject as well as the PLN-null mouse. Proteins were visualized with specific antibodies against PLN, SERCA2, and calsequestrin and quantified against a standard obtained from normal human donor heart. (b) Autoradiographic images of oligonucleotide-probed Northern blot of PLN (upper panel), using cardiac RNA from normal individuals and those with PLN-L39stop (III-4) and nonfamilial heart failure. The radiolabeled 60-base oligonucleotide, antisense to the PLN coding region, recognizes the three major PLN mRNAs (0.8, 1.8, and 3.0 kb). These blots were stained with methylene blue to demonstrate the RNA integrity and loading (lower panel). CSQ, calsequestrin; HF, heart failure patient; NL, normal donor.