PROTECTIVE PROTEIN FOR BETA-GALACTOSIDASE, PPGB, MAPS TO THE DISTAL IMPRINTING REGION OF MOUSE CHROMOSOME-2 BUT IS NOT IMPRINTED

Human chromosome 20 is conserved as a single seg ment on distal mouse chromosome (Chr) 2. PPGB, protective protein for beta-galactosidase, m aps to human chromosome 20q13.1, and from linkage analysis of two inte rspecific crosses incorporating the mouse reciprocal translocations, T (2;8)2Wa (T2Wa) and T(2;16)28H (T28H), we have mapped the mouse homolo gue, Ppgb, to the conserved region on distal mouse Chr 2. From the com bined data, the order of markers is T2Wa-Ada-Ppgb -D2Mit25-T28HH Loci mapping between the T2Wa and T28H breakpoints lie in a region that is subject to parental imprinting, and so expression of Ppgb was tested i n mice with maternal duplication/paternal deficiency and its reciproca l for the distal region of Chr 2. We have shown by reverse transcripti on-polymerase chain reaction (RT-PCR) that both parental alleles of Pp gb were expressed in the brain and kidney of 17.5-day-old embryos, 18. 5 day-old embryos, and newborn mice. Thus, Ppgb does not appear to be subject to imprinting effects in the mouse. (C) 1994 Academic Press, I nc.