Figure 2. Diverse Functions of the SPARC Family of Proteins.
Schematic representation that highlights some of the activities attributed to each class of SPARC family members with a functional EC domain. SPARC family members are represented with ovals; red: SPARC, pink: Hevin/SPL1, magenta: Testican/SPOCK, purple: SMOC-1 and -2. Each family member is secreted and has been shown to affect some aspect of extracellular activity either through regulation of ECM assembly/degradation or through regulation of cell surface receptor/ligand interaction. In the case of Hevin/SPL-1 and SPARC this includes regulation of synapse formation via as yet unidentified factors either in the ECM and/or on cell surfaces. Collagen fibrils are shown in yellow with blue and orange rectangles representing the N and C-propeptides, respectively. KS: Killer signal (secreted by “winning” cells in Drosophila), DDR2: discoidin domain receptor 2, MT-MMP: membrane-type metalloproteinase, BMP: bone morphogenic protein, Ten C: tenascin C, MAPK: mitogen-associated protein kinase.