Membrane localization of transporter associated with antigen processing (TAP)-like (ABCB9) visualized in vivo with a fluorescence protein-fusion technique
Membrane localization of transporter associated with antigen processing (TAP)-like (ABCB9) visualized in vivo with a fluorescence protein-fusion technique
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DOI：
10.1248/bpb.27.1916
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发表时间：
2004-12-01
影响因子：
2
通讯作者：
Maeda, M
中科院分区：
文献类型：
--
作者：
Kobayashi, A;Maeda, T;Maeda, M
与抗原加工相关的转运蛋白（TAP）样（TAPL，ABCB 9）是一种半型ATP结合盒（ABC）蛋白，属于与TAP高度同源的亚家族B，是由TAPI和TAP 2亚基组成的异源二聚体复合物。在其羧基末端用绿色荧光蛋白（GFP）标记的人TAPL（TAPL-GFP）在细胞内膜上显示与TAPL-GFP类似的荧光。截短形式的TAPL-L-GFP（（MS 275）-S-1_后接GFP）显示出与TAPL-GFP相似的细胞荧光模式。然而，TAPL-S-GFP（M-1-G（75））的荧光分布在包括质膜在内的所有细胞膜上，表明TAPL（M-1-S-275）的氨基末端区域对于其定位于细胞内膜是必需的。共表达研究表明，TAPL-S-GFP与TAPL-DR（DsRed标记的TAPL）或TAPL-DR共定位，表明TAPL不仅能够与自身相互作用，还能够通过TAPL的M-1-G（75）区域与TAPI相互作用。还提出TAPL的进一步下游序列将限制TAPL-S-GFP在细胞内膜的分布。类似地，TAP 2-S-GFP（M-1-R-88）的分布被TAPL-DR或TAPL-DR限制于细胞内膜，表明TAP 2的M-1-R-88区域能够与TAPL以及TAPI相互作用。因此，TAPL将与其自身形成同源二聚体，并与TAP 1和TAP 2形成异源二聚体。TAPL-GFP与荧光内质网（ER）标记物共定位，表明TAPL主要定位于细胞内膜中的ER。
Transporter associated with antigen processing (TAP)-like (TAPL, ABCB9) is a half-type ATP binding cassette (ABC) protein belonging to subfamily B highly homologous to the TAP, a hetero-dimeric complex consisting of a TAPI and a TAP2 subunit. Human TAPL, to which was tagged with green fluorescence protein (GFP) at its carboxyl terminus (TAPL-GFP), showed fluorescence on intracellular membranes similar to TAPL-GFP. A truncated form of TAPL-L-GFP ((MS275)-S-1_ was followed by GFP) showed a similar cellular fluorescence pattern to TAPL-GFP. However, the fluorescence of TAPL-S-GFP (M-1-G(75)) was distributed over all the cellular membranes including plasma membrane, indicating that the amino terminal region of TAPL (M-1-S-275) is essential for its localization to the intracellular membranes. A co-expression study demonstrated that TAPL-S-GFP was co-localized with TAPL-DR (DsRed-tagged TAPL) or TAPL-DR, suggesting that TAPL is able to interact with not only itself but also with TAPI through the M-1-G(75) region of TAPL. It is also proposed that a further downstream sequence of TAPL would confine t.he distribution of TAPL-S-GFP to the intracellular membranes. Similarly, the distribution of TAP2-S-GFP (M-1-R-88) was restricted to the intracellular membranes by TAPL-DR or TAPL-DR, indicating that the M-1-R-88 region of TAP2 is able to interact with TAPL as well as TAPI. Therefore, TAPL would form a homo-dimer with itself, and a hetero-dimer with TAP1 and TAP2. TAPL-GFP was co-localized with the fluorescence endoplasmic reticulum (ER) marker, suggesting that TAPL is mainly localized to the ER in the intracellular membranes.