Evidence for the existence of two assembly domains within the sea urchin fertilization envelope.
The sea urchin fertilization envelope (FE) is a complex, macromolecular aggregate assembled by the addition of cortical granule secretions to the vitelline layer. The completed, trilaminar structure has a dense layer sandwiched between surface coats of paracrystalline material. Two cortical granule enzymes, ovoperoxidase and protease, and a cell surface transglutaminase are required for the assembly process. We have examined, by quick-freeze, deep-etch, rotary-shadow electron microscopy, the effects of inhibiting each of these enzymes upon FE assembly. These experiments reveal two domains within the FE, distinguishable by their enzymatic requirements for proper maturation. The first domain consists of the microvillar casts which require both protease and transglutaminase activities to obtain a normal paracrystalline coat. The second domain comprises the regions between casts and appears to mature by ovoperoxidase-mediated cross-linking of paracrystalline material to the envelope.
Department of Zoology, Arizona State University, Tempe 85287.
N M
NM
Mozingo
D E
DE
Chandler
D000818:Animals; D003594:Cytoplasmic Granules / Q000201:enzymology / Q000648:ultrastructure; D003599:Cytoskeleton / Q000201:enzymology / Q000648:ultrastructure*; D046911:Macromolecular Substances; D008871:Microvilli / Q000201:enzymology / Q000648:ultrastructure; D009195:Peroxidase / Q000378:metabolism; D012617:Sea Urchins / Q000196:embryology* / Q000648:ultrastructure; D011503:Transglutaminases / Q000378:metabolism; D014817:Vitelline Membrane / Q000201:enzymology / Q000648:ultrastructure*
D046911:Macromolecular Substances; D009195:Peroxidase; D011503:Transglutaminases