3 GENES FOR PROTEIN PHOSPHATASE-1 MAP TO DIFFERENT HUMAN-CHROMOSOMES - SEQUENCE, EXPRESSION AND GENE LOCALIZATION OF PROTEIN SERINE THREONINE PHOSPHATASE-1-BETA (PPP1CB)/

Complementary DNA encoding a catalytic subunit of protein phosphatase 1, termed PP1 beta, was isolated from a human teratocarcinoma library. Hybridisation with different cDNA fragments showed that all human tis sues examined contained 3.1 kb, 4.0 kb and 5.4 kb PP1 beta mRNAs arisi ng from alternative splicing of the 3' noncoding region. The level of the 5.4 kb mRNA relative to the 3.1 kb mRNA was higher in skeletal mus cle than in other tissues and the PP1 beta/PPl alpha mRNA ratio in rab bit tissues was highest in skeletal muscle. The 3' noncoding region of PP1 beta showed extreme conservation (greater than or equal to 90% id entity) between man and rodents over 1.7 kb, suggesting that this regi on is of functional importance. The gene for human PP1 beta (PPP1CB) w as localised to chromosome 2 by analysis of somatic cell hybrid DNA an d mapped to band q23 by fluorescence in situ hybridisation. These data show that the genes for three protein phosphatase catalytic subunits PP1 alpha, PP1 beta, PP1 gamma are all located on different chromosome s.