Dymple, a Novel Dynamin-like High Molecular Weight GTPase Lacking a Proline-rich Carboxyl-terminal Domain in Mammalian Cells*
- Takahiro Kamimoto,
- Yasuo Nagai,
- Hiroshi Onogi,
- Yoshinao Muro‡,
- Takashi Wakabayashi and
- Masatoshi Hagiwara§¶
- From the Departments of Anatomy and ‡Dermatology, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466 and §Department of Endocrinology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113, Japan
Abstract
We have cloned human dymple, a novel dynamin family member. The full-length cDNA sequence encodes a protein composed of 736 amino acids with a molecular mass of 80 kDa. This amino acid sequence most resembles yeast DNM1P and VPS1P. Dymple lacks a proline-rich carboxyl-terminal domain through which dynamin binds to SH3 domains to be activated. Northern blot analysis revealed two transcript sizes of 2.5 and 4.2 kilobases with alternative polyadenylation at the highest levels in brain, skeletal muscle, and testis. It was further established that there are three patterns of alternative splicing producing in-frame deletions in the coding sequence of dymple in a tissue-specific manner. When overexpressed, wild-type dymple exhibited a punctate perinuclear cytoplasmic pattern, whereas an amino-terminal deletion mutant formed large aggregates bounded by a trans-Golgi network marker. Since dynamin participates in clathrin-mediated endocytosis through a well-characterized mechanism, the existence of a dynamin-like molecule in each specific vesicle transport pathway has been predicted. Our findings suggest that dymple may be the first example of such a subfamily in mammalian cells other than dynamin itself, although its precise role and membrane localization remain to be resolved.
Footnotes
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↵* This work was supported by grants from the Ministry of Education, Science, and Culture and the Ministry of Health and Welfare of Japan.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵¶ To whom correspondence should be addressed: Endocrinology Dept., Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113, Japan. Tel.: +81-3-5803-5836; Fax.: +81-3-5803-0248; E-mail: m.hagiwara.end{at}mri.tmd.ac.jp.
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↵1 The abbreviations used are: TGN, trans-Golgi network; mAb and pAb, monoclonal and polyclonal antibodies, respectively; AP, alkaline phosphatase; GST, glutathioneS-transferase; HA, hemagglutinin; RACE, rapid amplification of cDNA ends; PBS, phosphate-buffered saline; RT, reverse transcription; PCR, polymerase chain reaction; bp, base pair(s); kb, kilobase pairs; PK domain, pleckstrin homology.
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↵2 E. Conibear and T. H. Stevens, personal communication.
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- Received June 3, 1997.
- Revision received September 9, 1997.
- The American Society for Biochemistry and Molecular Biology, Inc.
