DNA sequences, gene regulation and modular protein evolution in the Drosophila 68C glue gene cluster
Abstract
The 68C locus of the Drosophila melanogaster polytene chromosomes contains the structural genes for three glue polypeptides (sgs-3, sgs-7 and sgs-8) synthesized in the larval salivary glands during the third larval instar. When the messenger RNAs for the glue polypeptides are being synthesized, the locus is puffed; the puff regresses in response to the steroid hormone ecdysterone. The three 68C glue mRNAs are coded in a gene cluster of less than 5000 base-pairs, and are expressed co-ordinately. In the experiments described here we show that the coordinate expression of these RNAs does not result from amplification of the puff DNA, nor is it associated with puff DNA rearrangement. We also report the nucleotide sequence of 6751 base-pairs of genomic DNA that includes the entire gene cluster, and describe coding and non-coding sequences with possible regulatory roles. In addition, we deduce the amino acid sequences of the primary translation products of the glue mRNAs, and show that the glue proteins form a diverged gene family. The members of the family all contain an amino-terminal hydrophobic block of amino acids, which is absent in the mature, secreted glue proteins, and a cysteine-rich carboxy-terminal module. sgs-3 differs from sgs-7 and sgs-8 by containing a third module between the other two, comprised largely of tandem repeats of the five amino acids Pro-Thr-Thr-Thr-Lys.
Additional Information
© 1983 Elsevier. Received 16 February 1983, Revised 31 March 1983. We thank Dr C. M. Rice for teaching us DNA sequencing methods, T. Hunkapiller for computer programs and instruction in their use, M. Douglas for aiding in preparing computer-generated Figures, and Dr Leroy Hood for the use of his computer facility. We also thank Dr G. Scherer, K. Burtis and H. Nick for communicating unpublished results, and Drs S. Scherer and M. Snyder for discussions and advice. Two of us (M.D.G. and R.E.P.) are predoctoral fellows of the National Science Foundation. This work was supported by grant 1 RO1 GM 28075 (awarded to E.M.M.) by the Institute of General Medical Sciences, National Institutes of Health, and by a National Reserch Service Award (1 T32 GM 07616), also from the National Institute of General Medical Sciences, National Institutes of Health.Additional details
- Eprint ID
- 72762
- DOI
- 10.1016/S0022-2836(83)80074-6
- Resolver ID
- CaltechAUTHORS:20161213-093113460
- NSF Predoctoral Fellowship
- 1 RO1 GM 28075
- NIH
- 1 T32 GM 07616
- NIH Predoctoral Fellowship
- Created
-
2016-12-13Created from EPrint's datestamp field
- Updated
-
2021-11-11Created from EPrint's last_modified field