• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2004.06a
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• pp.278-281
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• 2004

The $\alpha$1,6-mannosyltransferase encoded by Saccharomyces cerevisiae OCH1 plays a key role for the outer chain initiation of the N-linked oligosaccharides. A search for Hansenula polymorpha genes homologous to S. cerevisiae OCHI (ScOCH1) has revealed seven open reading frames (ORF100, ORF142, ORF168, ORF288, ORF379, ORF576, ORF580). All of the seven ORFs are predicted to be a type II integral membrane protein containing a transmembrane domain near the amino-terminal region and has a DXD motif, which has been found in the active site of many glycosyltransferases. Among this seven-membered OCH1 gene family of H. polymorpha, we have carried out a functional analysis of H. polymorpha ORF168 (HpOCH2) showing the highest identity to ScOCH1. Inactivation of this protein by disruption of corresponding gene resulted in several phenotypes suggestive of cell wall defects, including hypersensitivity to hygromycin B and sodium deoxycholate. The structural analysis of N-glycans synthesized in HpOCH2-disrupted strain (Hpoch2Δ) and the in vitro $\alpha$1,6-mannosyltransferase activity assay strongly indicate that HpOch2p is a key enzyme adding the first $\alpha$1,6-mannose residue on the core glycan Man$_{8}$GlcNAc$_2$. The Hpoch2Δ was further genetically engineered to synthesize a recombinant glycoprotein with the human compatible N-linked oligosaccharide, Man$_{5}$GlcNAc$_2$, by overexpression of the Aspergillus saitoi $\alpha$1,2-mannosidase with the 'HDEL” ER retention signal.gnal.

• Korean Journal of Digital Imaging in Medicine
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• v.6 no.1
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• pp.24-30
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• 2003

Flat-panel detector(FPD) is the driving force for realizing the next gene ration of x-ray system. In this study, we developed amorphous selenium(a-Se) based flat-panel digital X-ray detector(DXD) for radiography. The prototype detector consists of an amorphous selenium layer and a thin-film transistor(TFT) array. Comparing to other papers1)-4), optimization of amorphous selenium and progress of evaporation were similar. The pixel pitch of fabricated detector was $139{\mu}m$, fill factor was 86%, and the size was 14"${\times}$8.5". Hand and test bar pattern images were acquired. A high modulation transfer function(MTF) factor was obtained: 58% at 3.0 lp/mm.