The N-Terminal Domain of MYO18A Has an ATP-Insensitive Actin-Binding Site

详细信息    查看全文

• 作者：Yasushi Isogawa ; Takahide Kon ; Takeshi Inoue ; Reiko Ohkura ; Hisashi Yamakawa ; Osamu Ohara ; and Kazuo Sutoh
• 刊名：Biochemistry
• 出版年：2005
• 出版时间：April 26, 2005
• 年：2005
• 卷：44
• 期：16
• 页码：6190 - 6196
• 全文大小：417K
• 年卷期：v.44,no.16(April 26, 2005)
• ISSN：1520-4995

文摘

Myosin XVIII is the recently identified 18th class of myosins, and its members are composedof a unique N-terminal domain, a motor domain with an unusual sequence around the ATPase site, oneIQ motif, a segmented coiled-coil region for dimerization, and a C-terminal globular tail. To gain insightinto the functions of this unique myosin, we characterized its human homologue, MYO18A, focusing onthe functional roles of the characteristic N-terminal domain that contains a PDZ module known to mediateprotein-protein interaction. GFP-tagged full-length and C-terminally truncated MYO18A molecules thatwere expressed in HeLa cells exhibited colocalization with actin filaments. Chemical cross-linking ofthese molecules showed that they form stable dimers as expected from their putative coiled-coil tails.Cosedimentation of the various types of truncated MYO18A constructs with actin filaments indicated thepresence of an ATP-insensitive actin-binding site in the N-terminal domain. Further studies on truncatedconstructs of the N-terminal domain indicated that this actin-binding site is located outside the PDZ module,but within the middle region of this domain, which does not show any homology with the known actin-binding motifs. These results imply that this dimeric myosin might stably cross-link actin filaments bytwo ATP-insensitive actin-binding sites at the N-terminal domains for higher-order organization of theactin cytoskeleton.