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Biomedical subjects

M Poonian

Publications and source records attributed to M Poonian.

5 recordsLinked to original sources
PubMed1985

Olfactory neuron-specific protein is translated from a large poly(A)+ mRNA.

Poly(A)+ mRNA was isolated from rat olfactory mucosa and translated in a rabbit reticulocyte cell-free protein synthesizing system. Olfactory marker protein (OMP) of Mr 18,500 was faithfully produced by this system upon addition of mucosal mRNA. The protein was identified by radioimmunoprecipitation with specific anti-OMP serum and by competitive displacement of the radioactive product with authentic OMP. In addition, the immunoprecipitated product comigrated with OMP on NaDodSO4/polyacrylamide gels and on HPLC. In vitro synthesized OMP represented 0.5% of the total translational products. Total olfactory mucosal poly(A)+ mRNA is approximately 1.5-21 kilobases in size, as determined by denaturing agarose gels. Translational assays of gel-fractionated poly(A)+ mRNA demonstrated that OMP mRNA occurs in the 2.5- to 3.4-kilobase range. An mRNA of this size could code for a protein significantly larger than OMP. Since the in vitro synthesized OMP is indistinguishable in size from OMP isolated from tissue, our data indicate that OMP is synthesized directly without the intermediate formation of a larger polypeptide precursor. Thus, OMP mRNA contains untranslated regions that are four to five times larger than the coding region.

Animals↗
PubMed1985

Molecular cloning and regulated expression of the human c-myc gene in Escherichia coli and Saccharomyces cerevisiae: comparison of the protein products.

mRNA from human HL-60 cells was used to prepare a cDNA library, from which two full-length clones that encompass the complete c-myc coding region were isolated. One clone, pM1-11, contains all three exons of human c-myc. The second clone, pM4-10, represents a relatively rare transcript that initiated in the first intron and includes the coding exons 2 and 3. The cDNA insert in pM1-11 was used to express the human c-myc protein in both prokaryotic and eukaryotic cells. Insertion of the coding sequences in exons 2 and 3 into the appropriate expression vectors yielded detectable c-myc protein in Escherichia coli lacking the Lon protease and in Saccharomyces cerevisiae upon induction. The protein produced in E. coli has an apparent size of 60 kDa and appears to be unmodified, as it is identical in size to the protein synthesized in an in vitro system. In contrast, yeast cells synthesize two myc proteins, of 60 kDa and 62 kDa. The difference in apparent molecular mass between the two proteins appears to be due, in part, to phosphorylation. Subcellular fractionation of yeast cells showed that the c-myc phosphoprotein is located predominantly in the nuclear fraction.

Base Sequence↗