S100A6 binding protein and Siah-1 interacting protein (CacyBP/SIP): spotlight on properties and cellular function

The CacyBP/SIP protein (S100A6 binding protein and Siah-1 interacting protein) was originally discovered in Ehrlich ascites tumor cells as a S100A6 (calcyclin) target (Filipek and Wojda in Biochem J 320: 585-587, 1996; Filipek and Kuznicki in J Neurochem 70(5): 1793-1798, 1998) and later on as a Siah-1 interacting protein (Matsuzawa and Reed in Mol Cell 7(5): 915-926, 2001). CacyBP/SIP binds several target proteins such as some calcium binding proteins of the S100 family (Filipek et al. in J Biol Chem 277(32): 28848-28852, 2002), Skp1 (Matsuzawa and Reed in Mol Cell 7(5): 915-926, 2001), tubulin (Schneider et al. in Biochim Biophys Acta 1773(11): 1628-1636, 2007) and ERK1/2 (Kilanczyk et al. in Biochem Biophys Res Commun 380: 54-59, 2009). Studies concerning distribution of CacyBP/SIP show that it is present in various tissues and that a particularly high level of CacyBP/SIP is observed in brain (Jastrzebska et al. in J Histochem Cytochem 48(9): 1195-1202, 2000). Regarding the function of CacyBP/SIP, there are some reports suggesting its role in cellular processes such as ubiquitination, proliferation, differentiation, tumorigenesis, cytoskeletal rearrangement or regulation of transcription. This review describes the properties of CacyBP/SIP and summarizes all findings concerning its cellular function.