Biomedical subjects

Xin-Ying Yang

Publications and source records attributed to Xin-Ying Yang.

6 recordsLinked to original sources

PubMed2003

Bacterial expression, purification, and in vitro N-myristoylation of fusion hepatitis B virus preS1 with the native-type N-terminus.

Very low-level expression of hepatitis B virus (HBV) preS1 with the native-type N-terminus hampered the biochemical and functional studies on its myristoylation. In the present study, the fusion HBV preS1 with the native-type N-terminus and a His6-Tag fused to C-terminus (HBV preS1-HT) was highly expressed in Escherichia coli. This was due to an introduced mutation of the rare codon GGA found in the HBV preS1 to the codon preferred by E. coli, GGU. The protein was rapidly purified from bacterial lysate by Ni-IDA affinity chromatography. The experimental assays using 3H-labeled substrate demonstrate that the purified HBV preS1-HT can be effectively N-myristoylated by recombinant human protein N-myristoyltransferase (NMT) in vitro.

Acyltransferases↗

PubMed2003

Preparation of an anti-Cdx-2 antibody for analysis of different species Cdx-2 binding to acat2 promoter.

The homeodomain protein, Cdx-2, as transcription factor has been implicated in the transcriptional regulation of genes expressed in small intestine and the process of tumorgenesis. In current work, a conserved mouse Cdx-2 domain (mCdx-2D) coded by its cDNA fragment, which was amplified and cloned into the expression vector pGEX-4T1, was expressed as a fusion protein with GST (GST-mCd x-2D) and purified by one step of affinity chromatography. A polyclonal antibody against Cdx-2 was raised by using the recombinant fusion protein GST-mCdx-2D as antigen and was fractionated from the rabbit anti-serum. Western blot and EMSA (electrophoretic mobility shift assay) demonstrate that the natural and denatured Cdx-2s from different species (mouse and human) can be detected by the prepared anti-Cdx-2 antibody. Most notably, we found that the Cdx-2 in human intestine cell line Caco-2 is expressed in a differentiation-dependent manner and can efficiently bind to the mouse and human acat2 (acyl-coenzyme A: cholesterol acyltransferase 2) promoter regions, suggesting that the transcriptional factor Cdx-2 may play a role in regulating the acat2 expression in the intestinal cells.

Amino Acid Sequence↗

PubMed1999

Expression Purification and Activity ofhuman Myristoyl-CoA:N-myristoyltransferase.

A gene encodinghuman myristoyl-CoA: protein N-myristoyltransferase (hNMT) from a brain cDNA libraryhas been obtained by PCR amplification and DNA sequencing. Then the mature-type and His(6)-fusion-type expression plasmids (pMF-hNMT(3) and pMFHT-hNMT(2)) containing the hNMT gene under control of T7 promoter have been constructed and transformed into E. coli BL21(DE3). SDS-PAGE analysis showed that the recombinant hNMT products expressed at 37 degrees were almost unsoluble but most of the His(6)-hNMT product expressed at lower temperature (22 degrees ) was soluble and its yield was about 7% of the total soluble cellular proteins. By immobilized metal (Ni(2+)) chelation affinity chromatography up to 80% His(6)-hNMT was purified by one step from bacterial lysate. The labelling experiment in vitro domonstrated that the expressed and purified His(6)-hNMT had an obvious catalytic activity to transferring myristoyl group.

Journal Article↗

PubMed1997

The Construction and Functional Study of Protein Kinase Inhibitor Phage.

A DNA fragment, which encoded the heat-stable protein kinase inhibitor (PKI) (5-24) of camp-dependent protein kinase (cAPK), was synthesized and cloned into phage display vector fe-tet-DOG1. Thus, PKI(5-24) was displayed on the surface of phage fd, which was termed PKI phage (cAPK inhibitor phage), in a form fused with gene III protein (g3p). It was showed that PKI phage not only repressed cAPK effectively, but also bound with the immobilized recombinant His(6)-tag mouse cAPK-Calpha( His(6)-mCalpha) specifically. The bound PKI phages could be quantitatively eluted under acidic conditions. Model affinity screening demonstrated that PKI phages could be selectively enriched from the mixture of PKI phage and wild-type phages (1:10(8)) using affinity chromatography of immobilized His(6)-mCalpha. These results suggest that selecting protein kinase inhibitor by phage display technique is feasible.

Journal Article↗

PubMed1996

Cloning and Expression of the cDNA Coding for Rat Peptidylglycine alpha-Amidating Monooxygenase.

The dDNA of genes encoding rat peptidylglycine alpha-aminating monooxygenase(rPAM) were cloned and their expression in E. coli studied. Three DNA fragments were isolated from the rat brain cDNA library using the methods of plaque hybridization and PCR. DNA sequencing showed that they contained the total coding sequence for rPAM-2. By using the sited-directed mutation and PCR recombination methods, we obtained intact genes coding for the rPHM domain, the rPAL domain and rPAM, respectively. Different plasmids of these genes controlled under T(7) or P(L) promoter were constructed and transformed into E. coli. The high-level expression of rPAM-N260 in E. coli was first observed and its antiserum was prepared for the immunoassay of natural or recombinant PAMs. By the analysis with SDS-PAGE and Western blot, the products of rPHM and rPAM in E. coli were detected, and the amount of rPHM reached over 10% of the total bacterial proteins. It was found that low temperature and copper ion obviously increased the stability and solubility of the rPHM expressed in E. coli.

Journal Article↗

PubMed1996

A T7 Promoter-based Versatile Expression Vector System.

A family of T7 promoter-based versatile expression plamides for E. coli Were constructed. These vectors were featured strong T7 promoter, translational start, stop elements, a multiple cloning site with eight unique restriction sites in all three reading frames and f1 phage origin which allows packaging of single stranded plasmid, mutagensis and gene sequencing without subcloning steps. With these vectors recombinant proteins can be expressed in mature or short fusion forms. Many heterolegous genes have been highly expressed using these vectors, most of them were expressed in soluble and active forms.

Journal Article↗