A STUDY OF RARE EARTH BINDING MEMBRANE PROTEIN OF TETRAHYMENA PYRIFORMIS WITH RADIOTRACEP. I. EXTRACTION OF Ce, Yb, Tm BINDING MEMBRANE PROTEIN AND ITS MOL. WT. DETERMINATION

Tetrahymena pyriformis cells were first cultured in a proper medium in which R. E. tracer Ce-141, or Yb-169, or Tin-170 was spiked. It was assayed that 65% of the radioactivity localized in the cell pellicle. By a biochemical centrifuging procedure, pellicle was isolated from cilia, mitochondria etc……Membrane protein was extracted with a detergent, 2% sodium deoxycholate The compatible overlap of a protein elution peak and a radioactivity elution peak of the Sephadex G-100 gel chromatogram demonstrated the existanee of a R E. binding protein. By means of SDS-polyacrylamidegel electrophoresis a molecular weight of 54000 daltons of the protein was determined when compared with standard proteins.