PATL1 is a peripheral membrane protein. A, Immunoblots of Arabidopsis root subcellular fractions. Arabidopsis root extracts were centrifuged at 1,000g to yield a total cell extract (S1). The S1 fraction was centrifuged at 100,000g to yield soluble (S100) and membrane (P100) fractions. The S1, S100, and P100 fractions were analyzed by immunoblotting with antibodies to PATL1 and the integral membrane marker SEC12. Similar results were obtained in three independent experiments. B, Samples of the P100 fraction were washed in the indicated solutions. A total sample (T) was collected prior to centrifugation at 100,000g to yield the solubilized protein (S). Membrane equivalents of the T and S samples were analyzed by immunoblotting with antibodies to PATL1 or SEC12. Similar results were obtained in two independent experiments.