Mutagenic and functional analysis of the C-terminus of Saccharomyces cerevisiae Pho84 phosphate transporter.

A widely accepted mechanism for selective degradation of plasma membrane proteins is via ubiquitination and/or phosphorylation events. Such a regulated degradation has previously been suggested to rely on the presence of a specific SINNDAKSS sequence within the protein. Modification of a partly conserved SINNDAKSS-like sequence in the C-terminal tail of the Pho84 phosphate transporter, in combination with C-terminal fusion of green fluorescent protein or a MYC epitope, were used to evaluate the presence of this sequence and its role in the regulated degradation. The functional Pho84 mutants in which this SINNDAKSS-like sequence was altered or truncated were subjected to degradation like that of the wild type, suggesting that degradation of the Pho84 protein is regulated by factors other than properties of this sequence.