Arabidopsis thaliana Hsp100 proteins: kith and kin

Arabidopsis thaliana, the first plant for which the entire genome sequence is available, was also among the first plant species from which Hsp100 prot eins were characterized. The Athsp101 complementary DNA (cDNA) corresponds to the gene identification At1g74310 in the Arabidopsis genome sequence. An alysis of the genome revealed 7 additional proteins that are variably homol ogous with At1g74310 throughout the entire amino acid sequence and signific ant similarities or identities in the signature sequences conserved among H sp100 proteins. Although AtHsp101 is cytoplasmic, 5 of the 7 related protei ns have predicted plastidial localization signals. This complete descriptio n of the AtHsp100 family sets the stage for future research on expression a nd function.