6 S100 GENES ARE CLUSTERED ON HUMAN CHROMOSOME-1Q21 - IDENTIFICATION OF 2 GENES-CODING FOR THE 2 PREVIOUSLY UNREPORTED CALCIUM-BINDING PROTEIN-S100D AND PROTEIN-S100E

The human genome contains large regions that are highly structured. Se quence-related members of multigene families are often found in a clus tered organization. Here we describe a previously unrecognized gene cl uster composed of genes coding for calcium-binding proteins of the S10 0 family. The linkage of six S100 genes was established by pulsed-fiel d gel electrophoresis, and a contiguous DNA sequence of 15 kilobases c ontaining the full coding region of four different S100 genes was char acterized. This is the tightest mammalian gene duster discovered so fa r to our knowledge. Two additional S100 genes are located within the c luster, both of which exhibit unique structural features when compared with other S100 genes. The product of S100E is cysteine-rich, whereas that of S100D contains a long hydrophobic N-terminal tail. The gene c luster was assigned to chromosome 1q21, one of the bands showing rearr angements in neoplasms at high frequency. The deregulated expression o f some S100 genes in the duster during tumor progression suggests that chromosomal abnormalities may influence the expression of S100 genes in late stages of cancer, particularly in association with the formati on of metastases.