Structure and chromosomal localization of the human salivary mucin gene, MUC7.

We have isolated and characterized several MUC7 genomic clones encoding the human low-molecular-weight salivary mucin, MG2. The MUC7 gene spans approximately 10.0 kb and comprises of three exons and two introns. Intron 1 is approximately 1.7 kb long and is located in the 5'-untranslated region of the corresponding MUC7 cDNA. Intron 2 spans approximately 6.0 kb and is located close to the boundary of the putative leader peptide and secreted protein. The entire region encoding the secreted peptide is located on exon 3, spanning approximately 2.2 kb. The nucleotide sequence of sections of the MUC7 gene, including 1500 bp of the 5'-flanking region, was determined and analyzed for motifs identical or homologous to other known response elements. A modified RACE procedure was used to determine the 5'-end of the MUC7 mRNA. PCR, the human-hamster somatic cell hybrid panel PCRable DNAs kit, and an in situ hybridization analysis on the complete metaphase chromosome spreads were used for the chromosomal localization of the MUC7 gene. It was mapped to chromosome 4q13-q21.