Characterization of channel-forming activity in muscle biopsy from a porin-deficient human patient

A bioptic specimen from the muscles of a patient suffering from severe myopathy was inspectedfor the presence of human porin 31HL. Western blotting suggested that the specimen was freeof the most abundant eukaryotic porin 31HL (HVDAC1). The specimen was treated withdetergent and the soluble protein fraction was passed through a dry hydroxyapatite column.The passthrough of this column was inspected for channel formation in artificial lipid-bilayermembranes. The channel observed under these conditions had a single-channel conductanceof about 2.5 nS in 1 M KCl, was cation selective, and was found to be virtually voltageindependent. Experiments with a control specimen from a healthy human being, without anyindication for muscle myopathy, revealed the presence of the voltage-dependent porin 31HLin the sample. It is discussed whether the patient’s bioptic specimen contained another humanporin, which has not been studied to date in its natural environment.