Worm Breeder's Gazette 10(2): 137
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
We have been characterizing some of the genes from the hsp70 multigene family. We have recently sequenced two additional members of this family. The hsp70C gene is non-heat inducible and constitutively expressed, its mRNA is most abundant at the L1 larval stage. The hsp70C protein shares a high degree of identity with the rat grp78 protein (77% at the amino acid level). The rat grp78 protein is related to the hsp70 family and is found within the endoplasmic reticulum (Munro and Pelham, 1986, Cell 46, 291). The expression of the grp78 gene is enhanced when the cell or organism is starved of glucose. The hsp70C protein has a long, hydrophobic leader sequence and the COOH-terminal ER-retention signal sequence KDEL characteristic of the rat grp78 protein. Therefore, we conclude that the hsp70C gene is the grp78 equivalent in C. elegans.In a comparison with the hsp70C gene from C. briggsae, a high degree of homology in the coding and noncoding regions is observed. The 5' regulatory region of the two genes share several conserved blocks of sequences encompassing a heat shock element and copies of mammalian virus core enhancer sequences. One of these regions is highly conserved ( approximately 80%) with a sequence in the rat grp78 regulatory region. This region in the rat grp78 regulatory region is protected during nuclease footprinting studies (A. S. Lee, personal communication). We propose that this region may be involved in the glucose-mediated response. Another member of the hsp70 family characterized is the highly heat inducible gene hsp70D. We find that the hsp70D gene is closely related to both the hsp70C and grp78 genes (76% and 71% at the amino acid level respectively). As such, we identify the hsp70D gene as the first highly heat inducible variety of the grp78 subfamily. The COOH- terminal sequence is HDEL and not KDEL found in the hsp70C protein. Histidine is a conservative substitution of lysine and may function as an ER-retention signal. Only the last half of the hsp70D gene has been sequenced so we are unable to determine if the hsp70D gene, like the hsp70C gene, has a long, hydrophobic leader sequence.