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Immunohistochemical localization of cellCAM 105 in rat tissues: appearance in epithelia, platelets, and granulocytes
1Department of Medical and Physiological Chemistry, University of Uppsala, Sweden.
Abstract:
CellCAM 105 is an integral membrane glycoprotein, with apparent Mr 105,000, which has been purified from rat liver plasma membranes. It consists of two structurally similar, highly glycosylated polypeptide chains and is involved in cell-cell adhesion of adult rat hepatocytes in vitro. In this communication we report on the distribution and cell surface location of cellCAM 105 in rat tissues, obtained by using highly sensitive immunodetection systems based on complex formation between biotinylated antibodies, biotinylated peroxidase and avidin, or on antibodies coupled to alkaline phosphatase. CellCAM was found in many organs and organ systems, including liver, kidney, blood, blood vessels, glands, respiratory system, and gastrointestinal tract. It was mainly localized to epithelial structures but showed a varying cell surface distribution. In some cell types it was predominantly localized to cell-cell contact areas. In other cell types the highest concentrations were seen in brush-border areas containing densely packed microvilli. In addition to epithelial structures, cellCAM 105 was found in rat platelets, where it became strongly expressed on the cell surfaces after activation with ADP or collagen, suggesting that it might be involved in platelet adhesion and/or aggregation mechanisms. Granulocytes also contained cellCAM 105. By SDS-PAGE/immunoblotting, significant differences were found in the apparent Mr values of cellCAM 105 in different tissues. The collected data suggest that cellCAM 105 participates in several different cell surface membrane interactions, of which the common denominator might be membrane-membrane binding.
Insights
CellCAM 105, a cell adhesion glycoprotein, is found throughout rat tissues and on platelets. This protein plays a role in various cell-cell adhesion interactions, including those in epithelial structures and platelet aggregation.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- CellCAM 105 is an integral membrane glycoprotein purified from rat liver plasma membranes.
- It is composed of two glycosylated polypeptide chains and is implicated in hepatocyte cell-cell adhesion.
- Its precise distribution and function in various tissues were not fully elucidated.
Purpose of the Study:
- To investigate the distribution and cell surface localization of cellCAM 105 in different rat tissues.
- To explore the potential role of cellCAM 105 in cell-cell adhesion and platelet function.
- To analyze variations in cellCAM 105 molecular weight across different tissues.
Main Methods:
- Utilized sensitive immunodetection systems involving biotinylated antibodies, biotinylated peroxidase, avidin, and alkaline phosphatase-coupled antibodies.
- Performed SDS-PAGE/immunoblotting to analyze molecular weight differences.
- Investigated cellCAM 105 expression on activated rat platelets (ADP or collagen).
Main Results:
- CellCAM 105 was detected in numerous organs and systems, primarily in epithelial structures.
- Its cell surface distribution varied, observed at cell-cell contact areas and brush borders.
- CellCAM 105 was also found in platelets and granulocytes, with increased expression on activated platelets, suggesting roles in adhesion and aggregation.
- Apparent molecular weight of cellCAM 105 differed significantly among tissues.
Conclusions:
- CellCAM 105 is widely distributed in rat tissues and involved in diverse cell surface membrane interactions.
- The findings suggest a role for cellCAM 105 in cell-cell adhesion, epithelial structure maintenance, and platelet-mediated processes.
- The commonality in its function may involve membrane-membrane binding across various cell types.