NATIONAL INSITUTE FOR BASIC BIOLOGY

National Institute for Basic Biology

DIVISION OF CELL DIFFERENTIATION

Professor:
Yoshiaki Suzuki (until July)
Associate Professor:
Kohji Ueno
Research Associates:
Kaoru Ohno
Hiroki Kokubo (on leave)


The E complex is a homeotic gene complex which specifies the identities of abdominal segments in the silkworm, Bombyx mori. We have reported that the E complex is similar to the Drosophila bithorax complex. The E complex comprises three homeobox genes: Bombyx Ultrabithorax (Bm Ubx), Bombyx abdominal-A (Bm abd-A), and Bombyx Abdominal-B (Bm Abd-B). Since some types of mutations in the E complex cause abnormal development of abdominal legs, the E complex regulates development of abdominal legs. Analyses of two mutants, the ECa/ECa (additional crescent) and EN/EN (new additional crescent) mutants, which lack abdominal legs demonstrated that the Bm abd-A is deleted within the mutant chromosomes. Therefore, Bm abd-A may be an essential gene for development of abdominal legs.

The homeodomain proteins encoded by homeotic genes are proposed to act as transcriptional regulators on target genes. To determine the target genes of the Bm abd-A gene product, we biochemically analyzed the proteins that are expressed specifically in abdominal legs and found that a high molecular weight protein (p260/270) was expressed specifically in abdominal leg cells during early embryonic stages and disappeared by a late embryonic stage. p260/270 consists of two polypeptides with molecular weights of 260,000 and 270,000 daltons. We have established a purification procedure and have raised an antibody against p260/270. Immunoblot analysis of the ECa/ECa and EN/EN mutants demonstrated that the two mutants lacked p260/270.

cDNA cloning and sequencing demonstrated that p260 and p270 have structures similar to rat fatty acid synthase, which synthesizes palmitate. Most of enzymatic domains for palmitate synthesis were well conserved in the amino acid sequences of p260 and p270. Many viral, cytoskeletal and cell surface receptor proteins have been reported to be modified with palmitate at their cysteine residues. Some small GTP-binding, heterotrimeric G and G-protein-linked receptor proteins are known to be modified with palmitate via thioester linkages. Such modifications may be important in regulation of signal transduction. Purified p260/270 can transfer palmitate to cysteine residues of synthetic peptides in vitro. We propose that p260/270 may be involved in protein palmitoylation and may function in abdominal leg development.

Publication List:

Kokubo, H., Ueno, K., Amanai, K. and Suzuki, Y. (1997) Involvement of the Bombyx Scr gene in development of the silk gland. Develop. Biol. 186, 46-57
Ueno, K. and Suzuki, Y. (1997) p260/270 expressed in embryonic abdominal leg cells of Bombyx mori can transfer palmitate to peptides J. Biol. Chem. 272, 13519-13526

webmaster@nibb.ac.jp
Last Modified: 12:00, May 28, 1998