passages.id: split_4_test_973_passage
passages.type: progene_text
passages.text: In an earlier study ( Kimura , Y. , Kurzydlowski , K. , Tada , M. , and MacLennan , D. H. ( 1997 ) J. Biol. Chem. 272 , 15061 - 15064 ) , mutation of amino acids on one face of the phospholamban ( PLN ) transmembrane helix led to loss of PLN inhibition of sarco ( endo ) plasmic reticulum Ca(2+)-ATPase ( SERCA ) molecules .