Multiple Variable First Exons: A Mechanism for Cell- and Tissue-Specific Gene Regulation.

Focuses on the family of neural protocadherin (Pcdh) proteins encoded by closely linked mammalian gene clusters. Determination of the cell-specific expression of each Pcdh gene; Implication for combining variable-exon promoter activation and cis-splicing of the corresponding variable exon to the first constant exon; Association of genomic organization with genetic mechanism for directing distinct cell- and tissue-specific patterns of gene expression.