Exon structure at the human ACP1 locus supports alternative splicing model for f and s isozyme generation

The human ACP1 locus encodes a genetically polymorphic cytoplasmic low-molecular-weight acid phosphatase. Each of the common alleles encodes two isoforms, f and s. Both isozymes are of equal length (157 residues) but differ in sequence over an internal 34 residue segment. Substantial portions of the ACP1*A, *B and *C alleles common to Europeans have been sequenced. Six linearly positioned exons containing codons 14 to 157 were identified. Two exons of equal length (114bp) interspaced by a short (41bp), probably nonfunctional, intron encode the specific f and s segments, respectively. These findings strongly support an alternative RNA splicing hypothesis. In addition, three allele-specific base substitutions were encountered.