Biomedical subjects

Y R Hong

Publications and source records attributed to Y R Hong.

21 records · Page 2Linked to original sources

PubMed1993

An expression-packaging-processing vector which selects and maintains 7-kb DNA inserts in the blue T4 phage genome.

We have developed an efficient positive-selection vector to insert foreign DNA segments fused to the T4 ipIII gene (encoding internal protein IPIII) into the bacteriophage T4 genome. By using partial deletions of the T4 e gene, which encodes phage lysozyme, lysozyme activity required for plaque formation is used to select plasmid integrants which restore the e gene. In this work, we demonstrate that DNA inserts more than 7.0 kb in length can be incorporated into a T4 genome lacking the alt gene. In addition, the recombinant T4 not only contains a fusion gene driven by the T4 ipIII promoters, but also packages the fusion protein into the T4 capsid due to targeting by the IPIII portion. This expression-packaging-processing system shows that active IPIII::beta Gal fusion reporter protein is produced and packaged during phage infection.

Bacteriophage T4↗

PubMed1993

Protein folding studies in vivo with a bacteriophage T4 expression-packaging-processing vector that delivers encapsidated fusion proteins into bacteria.

A cloned phage T4 gene which expresses the nonessential capsid scaffold protein IPIII was modified to permit construction and packaging of protein fusions within the capsid. IPIII deletion phage packaged IPIII-beta-galactosidase, IPIII-beta-globin, and IPIII-beta-globin-beta-galactosidase fusion proteins; the latter protein fusion was specifically processed by the T4 gene 21 head morphogenetic proteinase in vivo at a consensus leu(ile)-P1-glu* cleavage site to regenerate beta-galactosidase. Phage inject IPIII-beta-galactosidase protein into bacteria, but less activity is recovered in infections of Escherichia coli dnaK or groEL mutants, suggesting that these host molecular chaperones are required for beta-galactosidase intracellular folding. This expression-packaging-processing (EPP) vector directs protein fusions into capsids for easy detection and purification and permits study of protein delivery and folding in bacteria.

Bacteriophage T4↗

PubMedDate not supplied

The expression of rac1 pseudogene in human tissues and in human brain tumors.

BACKGROUND: Recent studies have demonstrated that Rac is a regulator of cell morphology and growth. Rac1 gene appears to have involvement in tumorigenesis and metastatic potential. In our previous study of rac1 gene in 45 human brain tumors, rac1 pseudogene was found. The rac1 pseudogene is an intronless pseudogene and has a similarity of 86% with rac1 nucleotide sequence. The rac1 pseudogene contains 579 nucleotides and only 46 amino acids can be translated. Little is known about the expression of rac1 pseudogene in human tissues or tumors. MATERIALS AND METHODS: The expression of rac1 gene and rac1 pseudogene in different human tissues and brain tumors was investigated by the use of reverse transcriptase-polymerase chain reaction and Northern blotting. RESULTS: The rac1 gene is apparently expressed in these 8 human tissues. The rac1 pseudogene is also apparently expressed in human tissues except for brain tissue. The overexpression of rac1 gene in brain tumors was 8% (2/25) and the overexpression of rac1 pseudogene was 76.9% (20/26). Only two astrocytomas had overexpression of rac1 gene, compared with normal brain tissues. The overexpression of rac1 pseudogene was 6 of 9 in meningiomas, 7 of 9 in astrocytomas, and 7 of 8 in pituitary adenomas. CONCLUSIONS: High frequency of overexpression of rac1 pseudogene was detected in the human brain tumors when compared with that expressed in the normal brain tissues. Our study suggested that the rac1 pseudogene may play an important role of the tumorigenesis of brain.

Astrocytoma↗