Localization and functional role of a 41 kDa collagenase/gelatinase activity expressed in the sea urchin embryo.
The egg storage compartment of the sea urchin embryo was investigated for a protein destined for export to the extracellular matrices. Using an antiserum prepared against a 41 kDa collagenase/gelatinase localized to the extraembryonic matrices (the hyaline layer and basal lamina), the egg storage compartment was mapped for this antigen. Indirect immunofluorescence analysis revealed the 41 kDa collagenase/gelatinase in the cortical granules as well as a second compartment which was dispersed throughout the egg cytoplasm. High resolution immunogold labeling defined this cytoplasmic compartment as the yolk granule organelle. Gelatin substrate gel zymography revealed the presence of a 41 kDa gelatin cleavage activity in purified yolk granules. These results suggest a role for yolk granules in regulated protein export and challenge the traditional view of this organelle as a benign storage compartment for nutrients. In additional experiments, embryos grown in the presence of the 41 kDa cleavage activity or the anti-41 kDa antiserum had severely delayed gut formation and spicule elongation. These results demonstrate a requirement for defined levels of the 41 kDa activity in the extracellular matrices of the developing embryo.
Mayne
Janice
J
Department of Biochemistry, Memorial University of Newfoundland, St John's, Newfoundland, A1B 3X9 Canada.
Robinson
John J
JJ
D000818:Animals; D017364:Collagenases / Q000502:physiology*; D004527:Egg Proteins / Q000502:physiology; D019084:Fluorescent Antibody Technique, Indirect; D018093:Gelatinases / Q000502:physiology*; D007150:Immunohistochemistry; D008858:Microscopy, Phase-Contrast; D012617:Sea Urchins / Q000196:embryology* / Q000502:physiology
D004527:Egg Proteins; D017364:Collagenases; D018093:Gelatinases