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Zoological Research
Kunming Institute of Zoology, Chinese Academy of Sciences
ISSN: 2095-8137
Vol. 29, No. 4, 2008, pp. 386-398
Bioline Code: zr08060
Full paper language: Chinese
Document type: Research Article
Document available free of charge

Zoological Research, Vol. 29, No. 4, 2008, pp. 386-398

 en Mechanism of βγ-CAT Cell Nuclear Transportation andSelectively Killing of Tumor cells
HE Ying-ying; LIU Shu-bai; QIAN Jin-qiao; LEE Wen-hui & ZHANG Yun

Abstract

βγ-CAT is a naturally existing protein complex of non-lens bg-crystallin and trefoil factor, purified from Bombina maxima check for this species in other resources skin secretions. In HUVECs, βγ-CAT can be rapidly endocytosed via intracellular vacuole formation and translocated to the nucleus to regulate cell fuction. In this paper, we found that it contains conserved Walker B motifs (IILYDEPS, residues 6-13) and Walker A motifs (GQSLSGKS, residues 96-103) in the βγ-CAT a-subunit sequence. βγ-CAT showed potential NTP-binding and weak GTPase/ATPase activities in vitro. Through Western blotting analysis, we found that the a- and b-subunits of βγ-CAT participated in a 150 kDa SDS-stable protein complex formation, which also contained positive ubiquitination signals in the βγ-CAT treated HUVEC. Furthermore,under confocal microscopy, the immunofluorescence signals of ubiquitin and βγ-CAT subunits were co-localized in the vacuoles that were distributed in the cytoplasm and nucleus. In addition, βγ-CAT could induce several tumor cell’s detachment and apoptosis, and selectively kill tumor cells. These findings provide a clue to understand the mechanism of βγ-CAT endocysis and nuclear transport, and give an insight to investigate the possible occurrence of similar molecule’s cellular functions and action mechanisms of non-lens bg-crystallins and trefoil factors in mammals.

Keywords
Non-lens βγ-crystallin; Trefoil factor; βγ-CAT; GTP/ATPase; Tumor cells detachment and apoptosis; Ubiquitination; Nuclear targeting

 
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Alternative site location: http://www.zoores.ac.cn/

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