0000000000214926
AUTHOR
Jürgen Conrad
Characterization of the trimeric, self-recognizing Geodia cydonium lectin I.
A D-galactose-specific lectin I was extracted from the sponge Geodia cydonium and purified by affinity chromatography. The molecular weight of lectin I as determined by high-pressure liquid gel chromatography, was found to be 36500 +/- 1300. Disc gel electrophoresis in the presence and in the absence of sodium dodecyl sulfate showed that lectin I is a trimer composed of three different subunits (Mr: 13800, 13000 and 12200); two of the three subunits are linked by one disulfide bond. Isoelectric focusing gave a pI of 5.6 for the native molecule and a pI of 4.4 and of 7.4 for the subunits. The three subunits carry carbohydrate side chains, composed of D-galactose (94%) and of arabinose (5%). …
Identification and isolation of the primary aggregation factor from the cell membrane of the sponge Geodia cydonium
The primary aggregation factor (pAF) of sponge cells is a glycoprotein that is firmly associated with the cell membrane. Polyspecific antibodies (anti-GM) prepared from sera raised against membranes of cells from the siliceous sponge Geodia cydonium were found to inhibit initial aggregation of homologous cells. The inhibition of aggregation, caused by anti-GM was neutralized by pAF. The pAF had been successfully solubilized and enriched by affinity chromatography, gel filtration and density gradient centrifugation, if checked by polyacrylamide gel electrophoresis in the presence of urea. The Mr of the native pAF was approximately 40 000 as estimated by gel filtration; under denaturing condi…
Cell adhesion molecule in the hexactinellid Aphrocallistes vastus
Abstract The Hexactinellida sponge Aphrocallistes vastus contains a soluble aggregation factor (AF) whose purification has been described in this communication. It is characterized by a S° 20.w value of 37 and a buoyant density of 1.45 g/cm 3 . The AF is a glycoporteinaceous particle composed of three major protein species; no core structure could be visualized. In the presence of Ca 2+ , the AF causes secondary aggregation of single cells. The aggregation process is temperature, pH, and ionic strength independent within a broad range. Evidence is presented indicating that two (or more) AF molecules are required for the establishment of a stable cell: cell interaction. In contrast to the AF…
Cell-cell recognition system in gorgonians: description of the basic mechanism
The dissociation of the gorgonian Eunicella cavolinii (Koch) into single cells was successfully accomplished. These cells readily formed aggregates of a size of 2 100 μm during incubation in roller tubes; no aggregate formation was observed in non-rotating Petri dishes. The formation of aggregates was not influenced by Ca++, urea or trypsin; it was also independent of temperature (4° to 30°C) and pH (5.5–9.0). The intercellular material of the gorgonian contains a galactose-specific lectin, as determined by double diffusion experiments and haemagglutination inhibition experiments using a series of galactoglycoconjugates. This lectin converted the aggregation-susceptible cells to aggregation…