Isolation of a new member of the S100 protein family: amino acid sequence, tissue, and subcellular distribution.

Abstract

Abstract. A low molecular mass protein which we term S100L was isolated from bovine lung. S100L possesses many of the properties of brain S100 such as self association, Ca÷+-binding (2 sites per subunit) with moderate affinity, and exposure of a hydrophobic site upon Ca+÷-saturation. Antibodies to brain S100 proteins, however, do not cross react with S100L. Tryptic peptides derived from S100L were sequenced revealing similarity to other members of the S100 family. Oligonucleotide probes based on these sequences were used to screen a cDNA library derived from a bovine kidney cell line (MDBK). A 562-nucleotide cDNA was sequenced and found to contain the complete coding region of S100L. The predicted amino acid sequence displays striking similarity, yet is clearly distinct from other members of the S100 protein family. Polyclonal and monoclonal antibodies were raised against S100L and used to determine the tissue and subcellular distribution of this molecule. The S100L protein is expressed at high levels in bovine kidney and lung tissue, low levels in brain and intestine, with intermediate levels in muscle. The MDBK cell line was found to contain both S100L and the calpactin light chain, another member of this protein family. S100L was not found associated with a higher molecular mass subunit in MDBK cells while the calpactin light chain was tightly bound to the calpactin heavy chain. Double label immunofluorescence microscopy confirmed the observation that the calpactin light chain and S100L have a different distribution in these cells.

Binding of Ca2+ and Zn2+ to Human Nuclear S100A2 and Mutant Proteins

“…S100 proteins have been implicated in pleiotropic cellular events, with specific functions for each of the family members, such as cell cycle regulation, cell growth, cell differentiation, and motility. S100A2 (formerly called S100L) was first detected at high levels in a subset of cells in lung and kidney and moderately in liver, cardiac muscle, and skeletal muscle (15) and was later recognized as the product of a gene located on chromosome 1q21 (16). This protein is an unusual member of the S100 protein family because of its predominantly nuclear localization (17), compared with the cytosolic localization of the other S100 proteins.…”

S100A16, a Novel Calcium-binding Protein of the EF-hand Superfamily

“…Among the different human S100 genes, 17 are clustered on the human chromosome 1q21 (3), a region frequently involved in chromosomal rearrangement in cancers (4 -6). Expression patterns of some members, including S100A3, -A8, -A9, -A12, and -B, are tissue-and cell-specific (7-10), whereas S100A2, -A13, and -A16 are expressed in a wide variety of tissues (2,(11)(12)(13). S100 proteins play a role in Ca 2ϩ homeostasis, cell proliferation, migration, differentiation, and apoptosis.…”

RAGE and Its Ligands in Melanoma

“…S100A2 is mainly located in the nuclei of cells [164]. The function of S100A2 in cancer is not clear.…”