Identification of trichoplein, a novel keratin filament-binding protein
Identification of trichoplein, a novel keratin filament-binding protein
复制标题
DOI：
10.1242/jcs.01667
复制
发表时间：
2005-03-01
影响因子：
4
通讯作者：
Inagaki, M
中科院分区：
文献类型：
--
作者：
Nishizawa, M;Izawa, I;Inagaki, M
角蛋白8和18（K8/18）是简单上皮细胞中间丝（IF）的主要成分。我们在这里报告的一种新的蛋白质，命名为sputplein的鉴定。该蛋白质显示出低程度的序列相似性，透明质蛋白，果胶和肌球蛋白重链，是一个K8/18结合蛋白。在我们使用双杂交方法测试的多种IF蛋白与Apoplein之间的相互作用中，Apoplein与K16和K18显著相互作用，并且在一定程度上与K5、K6 a、K8和K14相互作用。在体外共沉降测定中，Escheraplein直接结合K8/18，但不与波形蛋白、结蛋白、肌动蛋白丝或微管结合。针对胰蛋白酶产生的抗体特异性识别细胞裂解物中相对分子质量为61 kDa的多肽。使用该抗体与K8/18复合免疫沉淀Trichoplein，免疫染色显示Trichoplein与HeLa细胞中的K8/18丝共定位。在极化的Caco-2细胞中，Ekaplein不仅与K8/18细丝在顶端区域共定位，而且还与桥粒斑蛋白（桥粒的一种成分）共定位。在小肠的吸收细胞中，K8/18纤维共定位在顶端皮质区，并集中在桥粒。两者合计，这些结果表明，tripplein是一种角蛋白结合蛋白，可能参与组织的顶端网络的角蛋白丝和桥粒在简单的上皮细胞。
Keratins 8 and 18 (K8/18) are major components of the intermediate filaments (IFs) of simple epithelia. We report here the identification of a novel protein termed trichoplein. This protein shows a low degree of sequence similarity to trichohyalin, plectin and myosin heavy chain, and is a K8/18-binding protein. Among interactions between trichoplein and various IF proteins that we tested using two-hybrid methods, trichoplein interacted significantly with K16 and K18, and to some extent with K5, K6a, K8 and K14. In in vitro co-sedimentation assays, trichoplein directly binds to K8/18, but not with vimentin, desmin, actin filaments or microtubules. An antibody raised against trichoplein specifically recognized a polypeptide with a relative molecular mass of 61 kDa in cell lysates. Trichoplein was immunoprecipitated using this antibody in a complex with K8/18 and immunostaining revealed that trichoplein colocalized with K8/18 filaments in HeLa cells. In polarized Caco-2 cells, trichoplein colocalized not only with K8/18 filaments in the apical region but also with desmoplakin, a constituent of desmosomes. In the absorptive cells of the small intestine, trichoplein colocalized with K8/18 filaments at the apical cortical region, and was also concentrated at desmosomes. Taken together, these results suggest that trichoplein is a keratin-binding protein that may be involved in the organization of the apical network of keratin filaments and desmosomes in simple epithelial cells.