label: RNA polymerase II CTD heptapeptide repeat Y1 phosphatase activity
label_lc: rna polymerase ii ctd heptapeptide repeat y1 phosphatase activity
description: "Catalysis of the reaction: RNA polymerase II large subunit CTD heptapeptide repeat--phospho-L-tyrosine (consensus YSPTSPS)(position 1) + H2O = RNA polymerase II large subunit + phosphate."