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Expression of the Rh-related glycoprotein (Rh50)
1Lindsley F. Kimball Research Institute, New York Blood Center, New York, N.Y. 10021, USA. ksuyama@nybc.org
Abstract:
The Rh50 glycoprotein is suspected of being involved in Rh antigen expression. We prepared Rh50 cDNA from a human bone marrow library by polymerase chain reaction and then subcloned this cDNA into various vectors. The vector containing Rh50 cDNA produced a 30-kDa nonglycosylated form of Rh50 in a rabbit reticulocyte lysate system and produced partially glycosylated Rh50 (32 kDa) when microsomes were added to the system. COS-1 cells transiently transfected with the vector containing Rh50 cDNA produced partially glycosylated Rh50 (32 kDa) recognized by a Rh50-specific antibody. Surface expression of Rh50 in K562 cells was also detected by flow cytometry using mouse monoclonal antibody (2D10) specific to Rh50. Partially glycosylated Rh50 (32 kDa) was again isolated from the lysates of K562 cells metabolically labeled with [35S]-methionine or [3H]-mannose using anti-Rh50 antisera. These systems (K562 and COS-1 cells) should prove useful for studying the transport of Rh proteins within the cell and the necessary components needed for Rh antigenicity at the cell surface.
Insights
Researchers identified the Rh50 glycoprotein
Area of Science:
- Molecular Biology
- Immunology
- Cell Biology
Background:
- The Rh50 glycoprotein's role in Rh antigen expression is under investigation.
- Understanding Rh50 is crucial for elucidating Rh blood group system genetics.
Purpose of the Study:
- To characterize the Rh50 glycoprotein.
- To investigate Rh50 expression and localization in cellular systems.
Main Methods:
- Polymerase chain reaction (PCR) was used to obtain Rh50 cDNA from human bone marrow.
- Rh50 cDNA was subcloned into vectors for expression in vitro (rabbit reticulocyte lysate) and in vivo (COS-1 and K562 cells).
- Expression and glycosylation of Rh50 were analyzed using Western blotting, flow cytometry, and metabolic labeling with [35S]-methionine and [3H]-mannose.
Main Results:
- A 30-kDa nonglycosylated Rh50 form was produced in vitro.
- Partially glycosylated Rh50 (32 kDa) was detected in the presence of microsomes and in transfected COS-1 cells.
- Surface expression of Rh50 was confirmed in K562 cells via flow cytometry using a specific monoclonal antibody (2D10).
- Metabolic labeling confirmed the presence of partially glycosylated Rh50 in K562 cells.
Conclusions:
- The study successfully expressed and characterized Rh50 glycoprotein.
- Established cellular systems (COS-1 and K562 cells) provide valuable models for studying Rh protein transport and cell surface antigenicity.
- Further research using these systems can advance understanding of Rh antigen function.