CLONING AND CHARACTERIZATION OF HUMAN PHOSPHATASE INHIBITOR-2 (IPP-2)SEQUENCES

cDNA clones similar to rabbit muscle phosphatase inhibitor-2 (IPP-2) w ere isolated from human libraries. On Northern blots two transcripts o f approximately 2kbp and approximately 4kbp were detected in all tissu es tested. Analysis of cDNA sequences showed that the longer transcrip ts were similar to the shorter clones but contained extended 3' ends. The human nucleotide sequence was highly homologous (94% identity) to the rabbit IPP-2 sequence and encoded a peptide of 205 amino acids. IP P-2 sequences were highly conserved throughout vertebrates. Southern h ybridization results were consistent with the existence of a family of related IPP-2 sequences in the human genome. Most of these are likely to be pseudogenes, since all of the cDNA clones examined could have o riginated from a single gene. By in situ hybridization IPP-2 sequences were mapped to several different human chromosomes. We sequenced one gene located in the major histocompatibility complex (MHC) on Chromoso me (Chr) 6 that contained the entire coding region of IPP-2.