Human CD44 Recombinant Protein

Product Specific Information

Description: CD44 is a cell membrane associated, polymorphic glycoprotein with apparent molecular weights ranging from 85 kDa to 250 kDa. CD44 isoforms participate in a wide variety of cell-cell or cell-matrix interactions including lymphocyte homing, establishment of B and T cell immune responses, tumor metastases formation and inflammation.

Three isoform categories of the CD44 molecule have been identified:

1) an 80-90 kDa isoform, the so-called standard form named CD44std, which is widely distributed on several hematopoietic and nonhemato-poietic cells including all subsets of leukocytes, monocytes, erythrocytes, many types of epithelium, mesenchymal elements like fibroblasts, smooth muscle cells and glial cells of the central nervous system,

2) a medium size category of 110-160 kDa which is weakly expressed on epithelial cells and highly expressed in some carcinomas and

3) a category which includes very large isoforms of 250 kDa covalently modified by the addition of chondroitin sulfate.

These bigger isoforms of CD44 arise by alternative splicing of one or more "variant" exons (v2-v10) into the extracellular part of the 90 kDa constant form molecule. Compared to the standard CD44, all larger isoforms are expressed in a much more restricted fashion, only in a few normal tissues or on the surface of certain tumor cells. Some splice variants of CD44 play important and distinct roles in tumor metastasis.

CD44 is known to interact with the ezrin family (ERM family) members and form a complex that plays diverse roles within both normal and abnormal cells, particularly cancer cells. CD44 and ezrin and their respective complex have properties suggesting that they may be important in the process of tumour-endothelium interactions, cell migrations, cell adhesion, tumour progression and metastasis. Determination of sCD44std will provide more detailed insight into different pathological modifications during cancer and other diseases.

Molecular Weight: 80-95 kDa.

Target Information

CD44 cell surface antigen is a 100 kDa type 1 transmembrane glycoprotein widely expressed on human leucocytes, white matter of the brain and by some epithelial cells of the intestine and breast. Several isoforms of CD44 exist, including the predominant CD44H isoform detected in many normal tissues. CD44 is a receptor for hyaluronic acid (HA) and is involved in cell-cell interactions, cell adhesion and migration. CD44 also participates in a wide variety of cellular functions including lymphocyte activation, recirculation and homing. CD44 expression may be up-regulated upon some carcinomas, and it has been speculated that this may be related to metastatic potential. CD44 is expressed by hematopoietic, non-hematopoietic cells, epithelial tissues, and to filopodia in cultured keratinocytes. Further, bone marrow myeloid cells and memory T cells express CD44 at high levels, and peripheral B and T cells can upregulate the expression of CD44 in response to certain stimulatory events. Transcripts for the CD44 gene undergo complex alternative splicing that results in many functionally distinct isoforms, however, the full-length nature of some of these variants have not been determined. Alternative splicing is the basis for the structural and functional diversity of the CD44 protein. Diseases associated with CD44 dysfunction include superficial keratitis and lichen sclerosus. CD44 also may be related to tumor metastasis formation.