Endo16, a lineage-specific protein of the sea urchin embryo, is first expressed just prior to gastrulation.
We have isolated and characterized a new endoderm-specific gene, designated Endo16, from a sea urchin gastrula stage cDNA library. Northern blot analysis and in situ hybridization experiments indicate that this gene is first expressed in the vegetal plate, a group of endodermal and mesenchymal precursor cells that are poised to invaginate in the first movement of gastrulation. Expression becomes progressively restricted to a subset of endodermal cells as development proceeds. To study the Endo16 gene product, a polyclonal antiserum was raised against bacterially expressed Endo16 protein. Indirect immunofluorescence experiments in midgastrula stage embryos reveal that the Endo16 protein is localized to the surface of endoderm and secondary mesenchyme cells. In Western blot experiments, the antiserum detects a small set of high molecular weight proteins ranging from 180 to greater than 300 kDa. Analysis of the nucleotide-derived amino acid sequence from a partial Endo16 cDNA clone reveals a highly repetitive, extremely acidic protein segment that includes the Arg-Gly-Asp (RGD) tripeptide known to be important in cell binding domains of a number of extracellular proteins. Taken together, these data suggest that the Endo16 protein may be an adhesion molecule involved in gastrulation of the sea urchin embryo.
Nocente-McGrath
C
C
Department of Biology, Tufts University, Medford, Massachusetts 02155.
Brenner
C A
CA
Ernst
S G
SG
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000235:genetics* / Q000276:immunology; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004707:Endoderm / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005775:Gastrula / Q000502:physiology*; D015870:Gene Expression; D007106:Immune Sera / Q000276:immunology; D008648:Mesoderm / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009693:Nucleic Acid Hybridization; D011506:Proteins / Q000235:genetics* / Q000276:immunology; D012617:Sea Urchins / Q000196:embryology* / Q000235:genetics; D013997:Time Factors
D015815:Cell Adhesion Molecules; D007106:Immune Sera; D011506:Proteins; C061515:endo16 protein, sea urchin; D004247:DNA