Two Drosophila actin genes in detail gene structure, protein structure and transcription during development

Recombinant DNA clones encoding the Drosophila melanogaster homolog of the vertebrate myosin light-chain-2 (MLC-2) gene have been isolated. This single-copy gene maps to the chromosomal locus 99E. The nucleotide sequence was determined for a 3.4-kilobase genomic fragment containing the gene and for two MLC-2 cDNA clones generated from late pupal mRNA. Comparison of these sequences shows that the gene contains two introns, the positions of which are conserved in the corresponding rat sequence. Extension of a primer homologous to the mRNA reveals two start sites for transcription 12 nucleotides apart. The sequence TATA is not present ahead of the mRNA cap site. There are two major sites of poly(A) addition separated by 356 nucleotides. The protein sequence derived from translation of the cDNA sequence shows a high degree of homology with that for the DTNB myosin light chain (MLC-2) of chicken. A lower degree of sequence homology was seen in comparisons with other evolutionarily related calcium-binding proteins. RNA blots show high levels of expression of several transcripts during the developmental time stages when muscle is being produced. In vitro translation of hybrid-selected RNA produces two polypeptides which comigrate on two-dimensional gels with proteins from Drosophila actomyosin, although the cDNA sequence reveals only one 26-kilodalton primary translation product.

“…The region hybridizing to late pupal cDNA was localized (14,48,49). We wished to determine whether the gene in pLP5734 conformed to this pattern.…”

Section: Resultsmentioning

confidence: 99%

“…t Present address: Amgen, Thousand Oaks, CA 91320. melanogaster. These components include the D. melanogaster actin (17,49), tropomyosin (2,25), myosin heavy chain (6,48) and myosin alkali light-chain genes (13,14). In this paper we describe the characterization of the MLC-2 gene of D. melanogaster.…”

mentioning

confidence: 99%

Characterization of the myosin light-chain-2 gene of Drosophila melanogaster.

Parker¹,

Falkenthal²,

Davidson³

1985

“…Insofar as they have been mapped, intron positions and sequences of the six genes are not conserved, with the exception of the intervening sequence at codon 307 which is present in the act88F and act79B genes (18,46). However, the protein-coding regions are rather highly conserved, and there is 85 to 95% amino acid sequence homology among the six actin isoforms.…”

mentioning

confidence: 99%

The Drosophila melanogaster actin 5C gene uses two transcription initiation sites and three polyadenylation sites to express multiple mRNA species.

Bond¹,

Davidson²

1986

101

At least six mRNAs are made from the Drosophila melanogaster act5C gene. We investigated the structures of these RNAs in detail and determined that they are heterogeneous at both their 5' and 3' ends. At the 5' end there were two nonhomologous leader exons which were alternately spliced to the remainder of the gene. These leader exons mapped to 1.7 and 0.7 kilobases, respectively, upstream of a common splice acceptor site which was eight base pairs 5' to the translation initiator AUG. Exon 1 is 147 bases in length, while exon 2 is 111 bases. A consensus TATA sequence was found roughly 30 base pairs upstream from exon 1, but none was found in the analogous position upstream of exon 2. The transcript length diversity arose principally from the use of three polyadenylation sites. This gave rise to RNA molecules with 3'-untranslated regions of roughly 375, 655, and 945 base pairs. With two start sites and three termination sites, this gene has the potential to produce six different transcripts. All six possible transcripts were present in whole fly mRNA. Transcripts containing the two different leader exons were found in roughly the same relative quantities through development. In contrast, the various 3' ends were differentially represented through development.

“…Differential expression of actin gene family members is well documented in metazoans, with the translated proteins falling into two general categories, muscle and cytoplasmic or cytoskeletal (8,10,11,13,17,(20)(21)(22)(23). Within these two categories, which have been defined largely by expression and not function, there are additional actin isoforms.…”

mentioning

confidence: 99%

“…Thus, there are at least two vertebrate cytoplasmic actins and at least four vertebrate muscle actins (22). In Drosophila melanogaster, an invertebrate, there are two cytoskeletal and four muscle actin genes which are expressed in characteristic patterns in developing and adult flies (11,17). Expression of particular actin genes thus seems to be associated with specific developmental pathways.…”

mentioning

confidence: 99%

Three sea urchin actin genes show different patterns of expression: muscle specific, embryo specific, and constitutive.

García¹,

Paz-Aliaga²,

Ernst³

et al. 1984

The expression of three different actin genes in the sea urchin, Strongylocentrotus purpuratus, was monitored in embryos and adult tissues by using untranslated mRNA sequences as specific hybridization probes. Three distinct patterns of expression were found: muscle specific, embryo specific, and constitutive (i.e., present in all tissues examined). The actin genes encoding the muscle-specific and constitutively expressed genes were each found to be present once in the haploid genome. The embryo-specific probe could derive from either a single gene or a small subset of actin genes. These data demonstrate that at least three members of the sea urchin actin gene family are expressed in distinct ways and thus are probably associated with different regulatory programs of gene expression necessary for development of this metazoan.