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Biomedical subjects

S Z Ao

Publications and source records attributed to S Z Ao.

8 recordsLinked to original sources
PubMed2001

Regulation of CDC42 GTPase by proline-rich tyrosine kinase 2 interacting with PSGAP, a novel pleckstrin homology and Src homology 3 domain containing rhoGAP protein.

Proline-rich tyrosine kinase 2 (PYK2), a tyrosine kinase structurally related to focal adhesion kinase (FAK), is implicated in regulating cytoskeletal organization. However, mechanisms by which PYK2 participates in and regulates cytoskeletal organization remain largely unknown. Here we report identification of PSGAP, a novel protein that interacts with PYK2 and FAK and contains multiple domains including a pleckstrin homology domain, a rhoGTPase-activating protein domain, and a Src homology 3 domain. PYK2 interacts with PSGAP Src homology 3 domain via the carboxyl-terminal proline-rich sequence. PSGAP is able to increase GTPase activity of CDC42 and RhoA in vitro and in vivo. Remarkably, PYK2, but not FAK, can activate CDC42 via inhibition of PSGAP-mediated GTP hydrolysis of CDC42. Moreover, PSGAP is localized at cell periphery in fibroblasts in a pleckstrin homology domain-dependent manner. Over expression of PSGAP in fibroblasts results in reorganization of cytoskeletal structures and changes of cellular morphology, which requires rhoGTPase-activating activity. Taken together, our results suggest that PSGAP is a signaling protein essential for PYK2 regulation of cytoskeletal organization via Rho family GTPases.

Amino Acid Sequence↗
PubMed1999

Identification of a novel gene encoding a p53-associated protein.

p53 exerts important physiological functions in cell-cycle control, gene regulation, cell differentiation, apoptosis and tumor suppression by interacting with many cellular proteins. Using the yeast two-hybrid system, we screened a HeLa cDNA library and identified a novel gene encoding a p53-binding protein (p53BP3). The full-length cDNA of p53BP3 was isolated from a HeLalambdagt10 cDNA library. This predicted protein was composed of 815 amino acids. Sequence analysis indicated that p53BP3 contained two bipartite nuclear localization signals and was confirmed to be a nuclear protein. FISH mapping results showed that this novel gene was located at human chromosome 12, region p11.2-p12.1. Northern blot analysis suggested that p53BP3 was broadly expressed in human tissues. A further study showed that p53BP3 had a homologue in mouse.

Amino Acid Sequence↗
PubMed1996

Ciliary neurotrophic factor antagonizes gentamicin-induced alterations of electric potentials in auditory pathway in guinea pigs.

AIM: To study the effects of ciliary neurotrophic factor (CNTF) on the expressions of gentamicin ototoxicity in guinea pigs. METHODS: The auditory function of pigmented guinea pigs was examined using auditory brainstem response (ABR), cochlea microphonic potential (CM), and action potential of auditory nerve (AP). RESULTS: In animals injected gentamicin (80 mg.kg-1.d-1, i.m.), ABR threshold began to elevate on d 20, and prolongations of ABR wave I, IV and the I-IV interpeak latencies were observed. The animals treated with gentamicin for 30 d displayed lower amplitudes of CM and AP (N1) than the controls. CNTF (0.44 mg.kg-1.d-1, s.c.) inhibited the gentamicin-induced elevation of ABR thresholds, the prolongation of ABR wave I, IV and the I-IV interpeak latencies, and the decreases in amplitudes of CM and AP (N1). CONCLUSION: CNTF attenuated the gentamicin-elicited auditory impairment in guinea pigs.

Action Potentials↗
PubMed1988

A persistent untranslated sequence within bacteriophage T4 DNA topoisomerase gene 60.

A 50-nucleotide untranslated region is shown to be present within the coding sequence of Escherichia coli bacteriophage T4 gene 60, which encodes one of the subunits for its type II DNA topoisomerase. This interruption is part of the transcribed messenger RNA and appears not to be removed before translation. Thus, the usual colinearity between messenger RNA and the encoded protein sequence apparently does not exist in this case. The interruption is bracketed by a direct repeat of five base pairs. A mechanism is proposed in which folding of the untranslated region brings together codons separated by the interruption so that the elongating ribosome may skip the 50 nucleotides during translation. The alternative possibility, that the protein is efficiently translated from a very minor and undetectable form of processed messenger RNA, seems unlikely, but has not been completely ruled out.

Amino Acid Sequence↗
PubMed1985

A new system for the synthesis of high levels of HBsAg sequence in Escherichia coli.

Using a system to study promoter activity, we have obtained a promoter fragment from E. coli chromosomal DNA. The HBsAg gene under the control of this promoter could be expressed in E. coli. The expression products are isolated and purified by means of a column of anti-HBs cross-linked to Sepharose 4 B. The pure products are characterized through the double diffusion method on 0.6% agarose and polyacrylamide-SDS gel electrophoresis. The synthesis of high levels of HBsAg sequences in E. coli is confirmed.

DNA Transposable Elements↗
PubMed1985

Expression of surface antigen gene of human hepatitis B virus serotype adr in Escherichia coli.

The construction of an expression plasmid of hepatitis B virus surface antigen (HBsAg) gene from the cloned hepatitis B virus (HBV) genome subtype adr is reported. The expression products of this plasmid in E. coli were detected by means of radioimmunoassay in competitive suppression and polyacrylamide-SDS gel electrophoresis. The presence of a fusion protein containing HBsAg was confirmed.

Escherichia coli↗
PubMed1984

The cloning and expression of the synthetic leu-enkephalin gene in E. coli.

The synthetic leu-enkephalin (LEK) gene was joined with pBR322 and transformed to E. coli. The recombinant plasmids containing the LEK gene were selected by colony hybridization, and characterized by restriction mapping and Southern's technique. The lac operon was used to control the expression of the LEK gene. A recombinant plasmid, pEL 103, in which the lac operon and LEK gene are transcribed in the same direction, produces LEK in E. coli. The level of LEK detected by radioimmunoassay reaches 426 ng per mg of bacterial protein.

Cloning, Molecular↗