Gene structure, sequence, and chromosomal localization of the human red cell-type low-molecular-weight acid...

Two distinct isoenzymes of the human red cell-type acid phosphatase (RCAP) have been known to exist for some time, but the genetic basis of this phenomenon was uncertain. We previously reported the isolation and characterization of two cDNA clones for human RCAP. We showed that the coding regions of the two cDNAs for the human isoenzymes were identical except for a divergent segment spanning nucleotides 176-274, called the variable region. We have now cloned, characterized, and mapped the gene encoding the red cell-type acid phosphatase isoenzymes. The human ACP1 gene is shown to span about 18 kb and to consist of seven exons. The promoter region of ACP1 is very GC-rich and has no apparent TATA or CCAAT boxes. The sequence information confirms that the variable regions of the isoenzymes exist in the gDNA sequence as separate and distinct exons, apparently subject to mutually exclusive alternative splicing. Using a genomic ACP1 clone, we have established the chromosomal localization of the gene to the distal portion of 2p25 by fluorescence in situ hybridization.