RESUMO
On the base of a cDNA fragment cloned from a human osteosarcoma cell line (HOS-8603) which was taken as the model of heat shock by DDRT-PCR, the cDNA library was screened by the probe made from this fragment, and the colony containing full length cDNA of this cDNA fragment (HSSG-1) was identified. Sequencing data indicated that this cDNA consisted of 1 456 bp, coding for 276 amino acids. Computer aided homology analysis did not find the same sequence published. The result of RNA dot hybridization suggested that HSSG-1 was expressing in many kinds of organs and cells, and the down regulating of its expression level caused by heat shock was general. Therefore, this may be a gene that is suppressed by heat shock.
RESUMO
In order to investigate the relationship between the structure of the mRNA translation initiation region (TIR) and gene expression, We mutated multiple sites of the 5' end of IFN-alpha8 and GM-CSF genes by site-directed mutagenesis without changing their amino acid sequences. SDS-PAGE showed that the protein products of mutated genes increased greatly in recombinant clones, as compared with their native genes. RNA dot blot revealed that the difference of their corresponding amount of mRNA transcribed between the native and the mutated genes was negligible. These results imply that the elevated expressions are attributed mainly to increased translation level. The prediction of mRNA secondary structure suggests that the delta G of TIR may have close relations to the expression level.