passages.id: split_7_validation_1373_passage
passages.type: progene_text
passages.text: Comparing the regions of BHMT amino acid sequence surrounding these Cys residues with similar amino acid sequences retrievable from protein databases , we have identified the following motif : G[ILV]NCX ( 20 , 100 ) [ ALV ] X(2) [ ILV ] GGCCX ( 3 ) PX ( 2 ) I , which we propose to be a signature for a family of zinc - dependent methyltransferases that utilize thiols or selenols as methyl acceptors .