Three vha Genes Encode Proteolipids ofCaenorhabditis elegans Vacuolar-type ATPase
GENE STRUCTURES AND PREFERENTIAL EXPRESSION IN AN H-SHAPED EXCRETORY CELL AND RECTAL CELLS*
- From the Department of Molecular Cell Biology, Division of Biological Science, Institute of Scientific and Industrial Research, Osaka University, Osaka 567, Japan
Abstract
The proteolipids of the vacuolar-type H+-ATPase (V-ATPase) are major components of the integral membrane sector. The vha-1 and vha-2(vacuolar-typeH +-ATPase) genes inCaenorhabditis elegans encode putative 16-kDa proteolipids and are tandemly localized on chromosome III. The vha-2gene has three exons, whereas vha-1 has no introns. The deduced amino acid sequences of the two genes exhibit about 60% identity with the homologues from yeast, mouse, and cow. The mRNAs of both vha genes are trans-spliced to spliced leaders, suggesting that these genes constitute a polycistronic transcriptional unit. The vha-4 gene consists of four exons and is very similar to the yeast VMA16 gene that codes for the 23-kDa proteolipid. This is the first example of three distinct V-ATPase proteolipids being identified in higher eukaryotes. Northern blot and transgenic analyses show that the three vha genes may be highly expressed in the H-shaped excretory cell, rectum, and a pair of cells posterior to the anus. These results suggest that the V-ATPase activity may be important for exporting toxic compounds or metabolic wastes in this organism.
Footnotes
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↵* This work was supported by grants from the Ministry of Education, Science, and Culture of Japan (to T. O.) and the Human Frontier Science Program Organization (to M. F.).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.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) AB000917, AB000918, and AB000919.
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↵‡ To whom correspondence should be addressed: Tel.: 81-6-879-8480; Fax: 81-6-875-5724; E-mail: m-futai{at}sanken.osaka-u.ac.jp.
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↵1 The abbreviations used are: V-ATPase, vacuolar-type H+-ATPase; SL, spliced leader; PCR, polymerase chain reaction; RT, reverse transcription; PCR, polymerase chain reaction; GFP, green fluorescent protein; kb, kilobase(s); bp, base pair(s).
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↵2 A. Fire, S. Xu, J. Ahnn, and G. Seydoux, personal communication.
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↵3 Y. Kohara, unpublished results.
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↵4 J. Burton, unpublished results.
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↵5 H. Nishigori, S. Yamada, A. A., Fernald, M. M., Lebeau, T. Takeuchi, and J. Takeda, manuscript in preparation.
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↵6 T. Oka, R. Yamamoto, and M. Futai, unpublished observation.
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- Received May 13, 1997.
- Revision received July 7, 1997.
