Phospholamban, the putative regulator of the Ca2+-ATPase in cardiac sarcoplasmic reticulum, was immunolocalized in canine visceral and vascular smooth muscle. Gently disrupted tissues were labeled with an affinity-purified phospholamban polyclonal antibody and indirect immunogold, using preembedding techniques. The sarcoplasmic reticulum of smooth muscle cells was specifically labeled with patc...
