Studies of pH Regulation by Btn1p, the Yeast Homolog of Human Cln3p

Although the gene responsible for Batten disease,CLN3,was positionally cloned in 1995, the function of Cln3p and the molecular basis of the disease still remain elusive. We previously reported that the yeastSaccharomyces cerevisiaecontains a homolog to Cln3p, designated Btn1p, and that the human Cln3p complemented the pH-dependent resistance tod-(−)-threo-2-amino-1-[p-nitrophenyl]-1,3-propanediol inbtn1-Δ yeast mutants. We have determined that yeast lacking Btn1p have an elevated ability to acidify media during growth that correlates with an elevated plasma membrane ATPase activity. Btn1p may be involved in maintaining pH homeostasis of yeast cells.