High impact information on CyIIa

• Organization of actin gene sequences in the sea urchin: molecular cloning of an intron-containing DNA sequence coding for a cytoplasmic actin [1].
• CyIIa, a cytoskeletal actin gene of Strongylocentrotus purpuratus, is expressed specifically though transiently in the embryonic skeletogenic and secondary mesenchyme and, later in development, is permanently activated in the hindgut and midgut [2].
• The CyI, CyIIa, and CyIIb genes are transcribed at a moderate rate that does not vary significantly during development [3].
• The single-copy bindin gene, the family of five cytoplasmic actin genes and the 400-fold-repeated set of five early histone genes were mostly unmethylated, but some sites exhibited partial methylation that varied throughout development [4].
• Nucleotide sequence comparisons of 5'-flanking region and intron DNA, however, indicate greater similarity between the CyI and CyIIb genes than the CyIIa gene that separates them, suggestive of a potential gene conversion event between the flanking genes in the CyI-CyIIa-CyIIb linkage [5].

Biological context of CyIIa

• The pattern of CyIIa expression is likely a consequence of these alternations in DNA sequence and protein-DNA interactions [6].
• A region in the CyIIa gene with limited identity to the functionally significant protein binding site D in CyI also did not bind protein [6].
• We also demonstrated that the DNA binding specificity of the CyIIa Ets-binding site can be converted to the other type of Ets site, as in the hatching enzyme promoter, by changing only three base pairs near the Ets core sequence [7].
• The similarity between CyIIa and CyI (and CyIIb) upstream sequences was limited and included a consensus octamer sequence, serum response element (SRE) and some short sequences within the proximal promoter region [6].
• The sequences corresponding to regions upstream of the ATG and transcription start site of the CyIIa cytoplasmic actin gene of the sea urchin Strongylocentrotus purpuratus were determined and compared to the genomically linked CyI and CyIIb actin genes [6].

Anatomical context of CyIIa

• Throughout gastrulation, CyIIa mRNA is expressed by a population of presumptive SMCs at the ventral aspect of the archenteron tip [8].
• Cytoplasmic actin, CyIII, is expressed in the aboral ectoderm cells of the indirect developers, but is an unexpressed pseudogene in H. erythrogramma, which lacks aboral ectoderm [9].

Other interactions of CyIIa

• Actin genes CyI, CyIIa, CyIIb, and M are expressed in both adult and embryonic tissues, giving rise to transcripts 2.1-2.2 kb in length [10].
• In S. franciscanus and S. dröbachiensis the first intron of the CyI gene has remained homologous with intron sequences of both the CyIIa and CyIIb genes, indicating a common origin of these three linked cytoskeletal actin genes [11].

References