• Title/Summary/Keyword: Autokinase

Search Result 4, Processing Time 0.015 seconds

The EphA8 Receptor Phosphorylates and Activates Low Molecular Weight Phosphotyrosine Protein Phosphatase in Vitro

  • Park, Soo-Chul
    • BMB Reports
    • /
    • v.36 no.3
    • /
    • pp.288-293
    • /
    • 2003

  • Low molecular weight phosphotyrosine protein phosphatase (LMW-PTP) has been implicated in modulating the EphB1-mediated signaling pathway. In this study, we demonstrated that the EphA8 receptor phosphorylates LMW-PTP in vitro. In addition, we discovered that mixing these two proteins leads to EphA8 dephosphorylation in the absence of phosphatase inhibitors. Finally, we demonstrated that LMW-PTP, modified by the EphA8 autokinase activity, possesses enhanced catalytic activity in vitro. These results suggest that LMW-PTP may also participate in a feedback-control mechanism of the EphA8 receptor autokinase activity in vivo.

  • https://doi.org/10.5483/BMBRep.2003.36.3.288 인용 PDF

Identification of Amino Acids Involved in the Sensory Function of the PrrB Histidine Kinase by Site-directed Mutagenesis (Site-directed mutagenesis에 의한 PrrB histidine kinase의 신호인지 기능에 관련된 아미노산의 발굴)

  • Kim Yong-Jin;Ko In-Jeong;Oh Jeong-Il
    • Journal of Life Science
    • /
    • v.16 no.3 s.76
    • /
    • pp.485-492
    • /
    • 2006

  • The PrrBA two-component system is one of the major regulatory systems that control expression of photosynthesis genes in response to changes in oxygen tension in the anoxygenic photosynthetic bacterium, Rhodobacter sphaeroides. The system consists of the PrrB histidine kinase and the PrrA response regulator. The N-terminal transmembrane domain of PrrB serves as a signal-sensing domain and comprises six transmembrane helices forming three periplasmic loops and two cytoplasmic loops. The $3^{rd}$ and $4^{th}$ transmembrane helices and the $2^{nd}$ periplasmic loop were suggested to play a crucial role in redox-sensory function. In this study we demonstrated that mutations of Asp-90, Gln-93, Leu-94, Leu-98, and Asn-106 in the $2^{nd}$ periplasmic loop and its neighboring region led to severe defects in PrrB sensory function, indicating that these amino acids might be related to the redox-sensing function of PrrB. The mutant forms (D90E, D90N, and D90A) of PrrB were heterologously overexpressed in Escherichia coli, purified by means of affinity chromatography and their autokinase activities were comparatively assessed. The D90N form of PrrB was shown to possess higher autokinase activity than the wild-type form of PrrB, whereas the D90E form of PrrB displayed lower autokinase activity than the wild-type form of PrrB. The D90A mutation led to the loss of PrrB autokinase activity.

  • https://doi.org/10.5352/JLS.2006.16.3.485 인용 PDF KSCI