Cell adhesion in sponges: potentiation by a cell surface 68 kDa proteoglycan-binding protein

1995 ◽  
Vol 108 (9) ◽  
pp. 3119-3126 ◽  
Author(s):  
J.A. Varner
Keyword(s):  
Cell Adhesion ◽  
Cell Surface ◽  
Intercellular Adhesion ◽  
Cell Surface Receptor ◽  
Sponge Cell ◽  
Cell Surfaces ◽  
Aggregation Factor ◽  
Surface Receptor ◽  
A Cell ◽  
Molecule Aggregation

Constitutive, stable intercellular adhesion is one of the distinguishing properties of metazoans, of which the sponges (Phylum Porifera) are the most primitive representatives. In sponges, intercellular adhesion is mediated by the large proteoglycan-like cell agglutinating molecule ‘aggregation factor’, which binds to cell surfaces via an oligosaccharide moiety. Previous studies indicated that this aggregation factor binds to two proteins associated with the surface of sponge cells. One of these, a 68 kDa peripheral membrane protein, was isolated by affinity chromatography on aggregation factor conjugated to Sepharose. This monomeric 68 kDa glycoprotein plays a key role in sponge cell adhesion since it potently inhibits the binding of aggregation factor to cell surfaces and completely prevents aggregation factor-mediated cell adhesion. The 68 kDa aggregation factor ligand binds with high affinity to both aggregation factor (KD = 2 × 10(−9) M) and cell surfaces (KD = 6 × 10(−8) M) providing evidence that it serves as an intramolecular bridge between the aggregation factor molecule and a cell surface receptor. Therefore, this early metazoan protein may represent one of the earliest extracellular matrix adhesion proteins to have arisen in the course of metazoan evolution.

P4-054: KLOTHO ENHANCES NEURONAL ACTIVITY THROUGH INTERACTION WITH A CELL-SURFACE RECEPTOR

2006 ◽  
Vol 14 (7S_Part_27) ◽  
pp. P1453-P1454
Author(s):  
Nicola J. Corbett ◽  
Kate Fisher ◽  
Helen A. Rowland ◽  
Alys C. Jones ◽  
Nigel M. Hooper
Keyword(s):  
Cell Surface ◽  
Neuronal Activity ◽  
Cell Surface Receptor ◽  
Surface Receptor ◽  
A Cell

230. Megalin, RAP and Nkx3.1 expression in the developing reproductive tract of a marsupial, the tammar wallaby

2008 ◽  
Vol 20 (9) ◽  
pp. 30
Author(s):  
M. Gamat ◽  
M. B. Renfree ◽  
A. J. Pask ◽  
G. Shaw
Keyword(s):  
Cell Surface ◽  
Reproductive Tract ◽  
Tammar Wallaby ◽  
Cell Surface Receptor ◽  
Urogenital Sinus ◽  
Receptor Associated Protein ◽  
Wide Range ◽  
Surface Receptor ◽  
A Cell ◽  
Strong Staining

Androgens induce the differentiation of the urogenital sinus (UGS) to form a prostate. An early marker of this response is upregulation of the transcription factor Nkx3.1 in the urogenital epithelium in the precursors of prostatic buds. In tammars, prostate differentiation begins ~3 weeks after birth and after the time the testis starts to secrete androgens, and 2 weeks after androgen stimulated Wolffian duct differentiation. The reason for this delay in prostate differentiation is unexplained. Androgen receptors are present in the UGS, and the potent androgen, androstanediol, induces prostatic development in females. Whilst androgens may diffuse into cells by across the cell membrane, there is increasing evidence that steroids are also internalised actively via the cell-surface transport molecule Megalin. We are exploring the possibility that the delay may be related to the establishment of a Megalin-mediated pathway. Megalin is a cell surface receptor expressed on epithelia and mediates the endocytosis of a wide range of ligands, including SHBG-bound sex steroids. Megalin action is regulated by Receptor Associated Protein (RAP), which acts as an antagonist to Megalin action. This study cloned partial sequences of Megalin, RAP and Nkx3.1 and examined their expression in the developing urogenital sinus of the tammar wallaby using RT–PCR. The cellular distribution of Megalin protein in the developing UGS was examined using immunohistochemistry. Megalin, RAP and Nkx3.1 in the tammar were all highly conserved with eutherian orthologueues. Megalin and Nkx3.1 transcripts were detected in the liver, kidney, ovary, testis and developing urogenital sinus of male and female tammars. In the developing UGS of the tammar, there was strong staining for Megalin protein in the urogenital epithelium with some diffuse staining in the surrounding mesenchyme. Together, these results suggest that Megalin could be a key gene in the mediation of androgen action in prostatic development in the tammar wallaby.

The T4 Glycoprotein Is a Cell-surface Receptor for the AIDS Virus

1986 ◽  
Vol 51 (0) ◽  
pp. 703-711 ◽  
Author(s):  
J.S. McDougal ◽  
P.J. Maddon ◽  
A.G. Dalgleish ◽  
P.R. Clapham ◽  
D.R. Littman ◽  
...  
Keyword(s):  
Cell Surface ◽  
Cell Surface Receptor ◽  
Aids Virus ◽  
Surface Receptor ◽  
A Cell

Thranbospondin Promotes Cell-and Platelet-Substratum Adhesion

1987 ◽  
Author(s):  
George P Tuszynski ◽  
Vicki L Rothman ◽  
Andrew Murphy ◽  
Katherine Siegler ◽  
Linda Smith ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Cell Surface ◽  
Polyacrylamide Gel Electrophoresis ◽  
Cell Types ◽  
Preliminary Evidence ◽  
Human Platelets ◽  
Cell Surface Receptor ◽  
Binding Assays ◽  
Surface Receptor

Thrombospondin (TSP), isolated from human platelets, promotes the in vitro, calcium-specific adhesion of a variety of cells, including platelets, melanoma cells, muscle cells, endothelial cells, fibroblasts, and epithelial cells. The cell adhesion-promoting activity of TSP is species independent since human, bovine, pig, rat and mouse cells all adhered to TSP. Furthermore, the cell adhesion-promoting activity of TSP is specific and not due to a nonspecific protein effect or to contamination by fibronectin, vitronectin, or laminin. That is, neither bovine serum albumin nor TSP preparations treated with a monospecific anti-TSP antibody support cell adhesion. As analyzed by polyacrylamide-gel electrophoresis and specific antibody binding assays, the TSP preparations used in these studies contained no detectable fibronectin or laminin and less than 0.04% vitronectin. The cell surface receptor for TSP appears distinct frcm that of fibronectin since an antiserum that blocks cell adhesion to fibronectin has no effect on adhesion to TSP. In addition, The platelet cell surface receptor for TSP appears distinct, frcm that of fibrinogen since thrcmbasthenic platelets adhere to TSP as well as control platelets. Antibodies to the GPIIb-GPIIIa complex block platelet adhesion to fibrinogen but have no effect on adhesion to TSP. Initial characterization of the cell surface receptor for TSP shows it to be protein in nature since cells treated with trypsin fail to adhere to TSP. In summary, our results provide the first clear evidence that TSP specifically promotes cell-substratum adhesion of a variety of cell types independent of the animal species. Our preliminary evidence suggests that the cell-surface receptor(s) for TSP is protein and that it is distinct for the receptor for fibronectin and fibrinogen. Our data suggest that TSP may play a central role in normal adhesive events mediated by platelets and other cells, such as those involved in hemostasis and wound healing. In addition, TSP may be involved in pathological adhesive events mediated by platelets and tumor cells, such as those involved in cardiovascular disease and tumor cell metastasis.

Membrane guanylate cyclase is a cell-surface receptor with homology to protein kinases

Nature ◽  
1988 ◽  
Vol 334 (6184) ◽  
pp. 708-712 ◽  
Author(s):  
Sujay Singh ◽  
David G. Lowe ◽  
David S. Thorpe ◽  
Henry Rodriguez ◽  
Wun-Jing Kuang ◽  
...  
Keyword(s):  
Cell Surface ◽  
Protein Kinases ◽  
Guanylate Cyclase ◽  
Cell Surface Receptor ◽  
Membrane Guanylate Cyclase ◽  
Surface Receptor ◽  
A Cell
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