Nakamura Noriko, Fujimoto Toyoshi
Department of Anatomy and Molecular Cell Biology, Graduate School of Medicine, Nagoya University, 65 Tsurumai, Showa, Nagoya 466-8550, Japan.
Biochem Biophys Res Commun. 2003 Jun 27;306(2):333-8. doi: 10.1016/s0006-291x(03)00979-3.
Adipose differentiation-related protein (ADRP) is a protein found in lipid droplets of many cell types. In contrast to several other proteins localized to lipid droplets, ADRP does not have a long hydrophobic domain. We investigated as to which portion of the molecule is important for localization to pre-existing lipid droplets. By truncating from the carboxyl-terminus, a segment of amino acids (aa) 1-181 of ADRP was found distributed to lipid droplets, but further deletion, e.g., aa 1-155, caused diffuse distribution in the cytoplasm. By amino terminal truncation, aa 167-426 was found mostly cytoplasmic, but surprisingly, a shorter mutant, e.g., aa 277-426, was distributed to lipid droplets. Still shorter mutants, e.g., aa 302-426, often distributed to mitochondria, and a mutant lacking aa 154-174 was found in the cytoplasm. Interestingly, expression of either aa 1-181 or aa 277-426, which are not overlapping each other, induced de novo formation of lipid droplets. The result indicates that ADRP has two independent domains related to its localization and lipid droplet biogenesis. The unique property found in the present study may be related to physiological function of ADRP.
脂肪分化相关蛋白（ADRP）是一种存在于多种细胞类型脂滴中的蛋白质。与定位于脂滴的其他几种蛋白质不同，ADRP没有长的疏水结构域。我们研究了该分子的哪一部分对于定位于预先存在的脂滴很重要。通过从羧基末端截断，发现ADRP的一段1 - 181氨基酸（aa）分布到脂滴中，但进一步缺失，例如1 - 155 aa，则导致在细胞质中呈弥漫分布。通过氨基末端截断，发现167 - 426 aa大多位于细胞质中，但令人惊讶的是，一个较短的突变体，例如277 - 426 aa，分布到了脂滴中。更短的突变体，例如302 - 426 aa，常常分布到线粒体中，而一个缺失154 - 174 aa的突变体存在于细胞质中。有趣的是，互不重叠的1 - 181 aa或277 - 426 aa的表达都诱导了脂滴的从头形成。结果表明，ADRP有两个与其定位和脂滴生物发生相关的独立结构域。本研究中发现的独特性质可能与ADRP的生理功能有关。
