鑑定phostensin 在細胞中的功能

Phostensin被鑑定為第一型蛋白質磷酸水解酶 (PP1) F-肌動蛋白細胞骨架的標靶次單元，其為KIAA1949 基因所轉錄之蛋白質。Phostensin基因位在人類的第六號染色體上，介於HLA-C和HLA-E基因叢之間。以北方點墨法分析顯示，phostensin的mRNA主要分布於白血球及脾臟中。目前發現Phostensin富含於輔助型T淋巴細胞、毒殺型T淋巴細胞、成熟的單核球細胞、巨噬細胞、B淋巴細胞、顆粒球細胞，以及自然殺手細胞中。在實驗室先前的結果證明，phostensin會與EHD1或EHD4進行結合。EHD蛋白被鑑定為調節特定內吞循環步驟的關鍵調控者。膜及膜蛋白的內化為所有真核生物所需之重要的細胞過程。有些膜蛋白具有內化性及針對性的降解作用。一部分的內化蛋白質會循環至細胞膜，而這些蛋白質能參與額外的內吞循環步驟。在本研究中，我想知道phostensin是否能調控膜蛋白的內吞運輸功能。我會選擇經由EHD蛋白調控的鐵運輸蛋白接受器作為我的分析模型。我會在實驗室先前確認過不表達phostensin的HeLa細胞中，將phostensin過度表達，鑑定其是否會影響鐵運輸蛋白接受器的內吞運輸功能。

關鍵字

內吞循環途徑； esp15 homology domain (EHD)蛋白家族；內吞作用

並列摘要

Phostensin, a protein phosphatase-1 F-actin cytoskeleton targeting subunit, is encoded by KIAA1949. The genomic location of phostensin is between the HLA-C and HLA-E gene clusters on human chromosome 6. Northern blot analysis indicated that phostensin mRNA was predominantly distributed in leukocytes and spleen. Phostensin is abundant in helper T-lymphocytes, cytotoxic T-lymphocytes, mature monocytes, macrophages, B- lymphocytes, granulocytes and natural killer cells. The preliminary results in our laboratory have demonstrated that phostensin binds to EHD1 or to EHD4. EHD proteins have been characterized as a key regulator in mediating specific endoctyic recycling steps. Internalization of membranes and membrane proteins is an essential cellular process required by all eukaryotic cells. Some membrane proteins are internalized and targeted for degradation. Part of internalized proteins is recycled to the plasma membrane where these proteins can participate in an additional endocytic recycling. In this study, I would like to ask whether phostensin regulates the endocytic transport of membrane proteins. I used transferrin receptor whose endocytic transport is regulated by EHD proteins in Hela cells as my assay models. I characterized whether the endocytic transport of this receptor is affected when phostensin has been overexpressed.

並列關鍵字

EHD1 ； KIAA1949 ； phostensin ； endocytosis

參考文獻

1. Olsen, J.V., et al., Quantitative phosphoproteomics reveals widespread full phosphorylation site occupancy during mitosis. Sci Signal, 2010. 3(104): p. ra3.

2. Lin, Q., et al., Molecular evolution of type 1 serine/threonine protein phosphatases. Mol Phylogenet Evol, 1999. 12(1): p. 57-66.

3. Virshup, D.M. and S. Shenolikar, From promiscuity to precision: protein phosphatases get a makeover. Mol Cell, 2009. 33(5): p. 537-45.

4. da Cruz e Silva, E.F., et al., Differential expression of protein phosphatase 1 isoforms in mammalian brain. J Neurosci, 1995. 15(5 Pt 1): p. 3375-89.

6. Faux, M.C. and J.D. Scott, More on target with protein phosphorylation: conferring specificity by location. Trends Biochem Sci, 1996. 21(8): p. 312-5.

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鑑定phostensin 在細胞中的功能

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