Detection and expression of the 70 kDa heat shock protein SSB1P at different temperatures in Saccharomyces cerevisiae.

Ssb1p and ssb2p are two members of the hsp70 family in yeast. Up to now there has been no evidence to indicate any differences between these two members of the hsp70 family, and it was suggested that ssb1p and ssb2p were 99% identical. Here we show that an antibody prepared against the C-terminal domain of human hsp71 recognizes specifically ssb1p out of the eight hsp(c)70s in Saccharomyces cerevisiae. An amino acid peptide sequence at the C-terminal end (VTATDKSTGK) is suggested to be the sequence which has high homology between ssb1p and hu-hsp71 and to be responsible for the specificity of recognition of this unique member of the hsp70 family. Using this antibody in immunoblot assays, we have determined the cellular content of ssb1p after heat shock and at different growth temperatures. Ssb1p is shown to be degraded during heat shock treatment while it shows a higher level of expression at low temperatures.