Recombinant Human M-Cadherin/Cadherin-15 Fc Chimera, CF

M-Cadherin (M-CAD or Cadherin-15) is a 124 kDa type I transmembrane glycoprotein of the Cadherin superfamily of calcium-dependent homotypic adhesion molecules (1 - 4). Like other classical Cadherins, the 814 amino acid (aa) human M-CAD contains a signal sequence (21 aa), a propeptide (29 aa), an extracellular domain with five Cadherin domain repeats (ECD, 556 aa), a transmembrane segment (20 aa) and a cytoplasmic domain (188 aa) (1). A splice variant that diverges within the third Cadherin repeat has been sequenced. The Cadherin repeats are responsible for cell-cell adhesion by homophilic binding on opposing cells (1 - 4). Intracellularly, M-CAD binds beta-catenin or plakoglobin ( gamma-catenin), which in turn bind alpha-catenin (4). M-CAD also binds p120 catenin (5). Connection of Cadherin/catenin complexes to the actin cytoskeleton is in question, but is possible through a linker (6). Connection to microtubules has been shown (7). M-CAD is present during early stages of skeletal muscle development and is thought to align myoblasts for fusion (8). It is also present in muscle satellite cells and participates in muscle regeneration (9). M-CAD is also expressed in the granule cell layer of the cerebellar glomerulus (10). Deletion of mouse M-CAD has little effect in vivo, most likely due to compensation by N-Cadherin (11). However, M-CAD upregulation and adhesion between myoblasts during induction of differentiation in vitro is required for their fusion (8, 12, 13). M-CAD activity is later downregulated by sequestering to caveoli, p120 catenin/RhoA-induced ubiquitination and/or cleavage by calpain-3. This terminates fusion and allows sarcomere formation (5, 12, 13). Human M-CAD ECD shows 88% aa identity with mouse, rat or bovine, and 85% aa identity with canine M-CAD ECD. M-CAD is an outlier among classical Cadherins, with 40% aa identity or less in the ECD (4).