title: Aggregation of sponge cells. XX. Self-aggregation of the circular proteid particle.
abstract: In the extracellular space of the tissue of the sponge Geodia cydonium, circular proteid particles are found which carry as subunits the aggregation factor and a series of glycosyltransferases. Using the technique of velocity sucrose gradient centrifugation, the sedimentation coefficient (S020,w) of the particle-monosomes was determined to be 90. By means of the Svedberg equation a molecular weight of 1.3 . 10(8) daltons could be estimated. The monosomes aggregate in the presence of Ca2+ to higher complexes via disomes, trisomes, and pentasomes. The complexes can be redissociated by dodecyl sulfate but not by EDTA. During the Ca2+-mediated self-aggregation, the particles lose their biological activity with respect to their aggregation promoting function.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002449:Cell Aggregation / Q000187:drug effects; D002462:Cell Membrane / Q000502:physiology; D008274:Magnesium / Q000494:pharmacology; D008565:Membrane Proteins / Q000502:physiology*; D011161:Porifera / Q000187:drug effects / Q000502:physiology*
chemical_list: D008565:Membrane Proteins; D008274:Magnesium; D002118:Calcium