The gene encoding endopolygalacturonase (EC 22.214.171.124) has been cloned, sequenced and expressed from three strains of Saccharomyces cerevisiae (including nonsecretors) and three strains of Kluyeromyces marxianus. Both control and coding regions showed small differences within each species, one including loss of a potential glycosylation site. Two non-secreting S. cerevisiae strains (FY1679 and var. uvarum) had non-transcribed copies of functional genes. Maximum enzyme activity was achieved with the S. cerevisiae FY1679 gene in an expressing vector, with an enzyme activity of 51 mu mol of reducing sugar released from polygalacturonic acid mug protein(-1) min(-1), the highest so far reported for a yeast.