Structure and Localization on the X Chromosome of the Gene Coding for the Human Filopodial Protein Moesin (MSN)

Moesin is a member of a recently discovered family of closely related proteins that includes ezrin, radixin, and merlin. It is widely expressed in different tissues and cells and has been localized to filopodia and other membranous protrusions that are important for cell-cell recognition and signaling and cell movement. Here, we have localized the coding gene (MSN) to Xq11.2-q12 by Southern and Western blot analyses of Chinese hamster × human somatic cell hybrids and by fluorescence chromosomal in situ hybridization. Moesin-like sequences were identified on chromosomes 5 and 6. The murine Msn locus was mapped to the X chromosome as well by studying a rodent × mouse hybrid panel. The structure of the human moesin gene has been determined. The 12 exons are distributed over >30 kb, and the exon/intron junctions demarcate individual highly conserved domains. Primer extension analysis revealed two major start transcription sites, 184 and 133 bp upstream of the initiation codon. The 5′-flanking region is GC-rich, lacks a TATA box, and contains four SP1 and one AP1 binding sites.