Promoter structure and protein sequence of msp130, a lipid-anchored sea urchin glycoprotein

The early fate specification of primary mesenchyme cells in sea urchin embryos makes them an attractive system for studying alterations in gene expression and protein synthesis during cell lineage determination and differentiation. To analyze the developmental regulation of gene expression in Strongylocentrotus purpuratus, we have isolated and sequenced genomic and cDNA clones encoding msp 130, a mesenchyme-specific cell surface glycoprotein. We have located the transcription initiation site of the msp130 gene and sequenced several kilobases of the promoter region. The region of the gene that encodes the protein is divided into numerous small (less than 500 base pairs) exons. The msp130 protein possesses two novel glycine-rich domains and a signal peptide, but apparently lacks a transmembrane domain. The carboxyl-terminal sequence suggests that msp130 may be phosphatidylinositol-linked to the cell membrane, and experiments with phospholipases support this conclusion. The implications of the msp130 sequence for its possible functions are discussed.