S100 family

The S100 protein family are clustered on chromosome 1q212.























strongly expressed in 50% of breast carcinomas, correlating with tumour grade6






S100A8, calgranulin A




S100A9, calgranulin B




S100A10, calpactin light chain




S100A11, S100C, calgrizzarin

inhibits the actin-activated myosin Mg(2+)-ATPase activity of smooth muscle3, targets annexin I, a phospholipid-binding protein involved in EGF receptor sorting4

expressed in nuclei of most epithelia; carcinomas show both nuclear and cytoplasmic immunoreactivity.5






S100A11 has 43% homology with S100 alpha and 43% homology with S100 beta1.

S100A9 is expressed in some breast carcinomas, expression correlating with high grade and lack of oestrogen receptor expression7.

1Watanabe, M., Y. Ando, et al. (1991). "Molecular cloning and sequencing of a cDNA clone encoding a new calcium binding protein, named calgizzarin, from rabbit lung." Biochem Biophys Res Commun 181(2): 644-9.

2Wicki, R., I. Marenholz, et al. (1996). "Characterization of the human S100A12 (calgranulin C, p6, CAAF1, CGRP) gene, a new member of the S100 gene cluster on chromosome 1q21." Cell Calcium 20(6): 459-64.

3Zhao, X. Q., M. Naka, et al. (2000). "Ca(2+)-dependent inhibition of actin-activated myosin ATPase activity by S100C (S100A11), a novel member of the S100 protein family." Biochem Biophys Res Commun 267(1): 77-9.

4Rintala, A. C., B. O. Schonekess, et al. (2002). "1H, 15N and 13C resonance assignments of rabbit apo-S100A11." J Biomol NMR 22(2): 191-2.

5Cross SS et al. S100A11 protein is overexpressed in common human cancers with spatial translocation from the nucleus to cytoplasm. Pathological Society Juy 2004, abstract 43.

6Cross SS et al. S100A6 protein is overexpressed in breast cancers and is significantly assocaited with increasing tumour grade but not with axillary lymph node metastases. Pathological Society, July 2004, abstract 56.

7Cross SS et al. S100A9 protein is overexpressed in some breast cancers and is significantly assocaited with increasing tumour grade and negative oestrogen receptor status. Pathological Society, January 2005, abstract 31.