How to use this site?
Please click on the comments to see the right option from the choices given
Dear Medicos,
This site contains a comprehensive list of medical PG entrance questions asked in various PG entrance examination throughout India like AIIMS, AIPGEE, PGI CHANDIGARH, JIPMER, CMC VELLORE .... and various state entrance exams like KERALA, TAMIL NADU, KARNATAKA, DELHI .... and also private entrances like COMEDK, MANIPAL etc...
1 comment:
4. CD 34.
CD34 molecule is a cluster of differentiation molecules present on certain cells within the human body. It is a cell surface glycoprotein and functions as a cell-cell adhesion factor. It may also mediate the attachment of stem cells to bone marrow extracellular matrix or directly to stromal cells.
The cluster of differentiation (cluster of designation) (often abbreviated as CD) is a protocol used for the identification and investigation of cell surface molecules present on white blood cells, providing targets for immunophenotyping of cells. Physiologically, CD molecules can act in numerous ways, often acting as receptors or ligands (the molecule that activates a receptor) important to the cell. A signal cascade is usually initiated, altering the behavior of the cell (see cell signaling). Some CD proteins do not play a role in cell signaling, but have other functions, such as cell adhesion.
The CD34 protein is a member of a family of single-pass transmembrane sialomucin proteins that show expression on early hematopoietic and vascular-associated tissue.
CD34 is also an important adhesion molecule and is required for T cells to enter lymph nodes. It is expressed on lymph node endothelia whereas the L-selectin to which it binds is on the T cell.
Conversely, under other circumstances CD34 has been shown to act as molecular "Teflon" and block mast cell adhesion, or to facilitate opening of vascular lumens.
Regardless of their mode of action, under all circumstances CD34 and its relatives, podocalyxin and endoglycan, have been shown to facilitate cell migration.
Post a Comment