The chromosomal localization of human beta-galactosidase revisited: a locus for beta-galactosidase on human chromosome 3 and for its protective protein on human chromosome 22.
A series of man-Chinese hamster and man-mouse somatic cell hybrids was investigated to study the localization of the genes coding for the human lysosomal enzyme beta-galactosidase (EC 3.2.1.23) and for its protective protein. Using a monoclonal antibody, raised against human placental beta-galactosidase, it was observed that the structural locus for the beta-galactosidase polypeptide is located on chromosome 3. The nature of the involvement of chromosome 22 in the expression of human beta-galactosidase was elucidated by metabolic labelling of the hybrids with radioactive amino acids, immunoprecipitation with monoclonal and polyclonal antibodies against beta-galactosidase, followed by analysis via gel electrophoresis and fluorography. The data show that the presence of chromosome 22 coincides with the presence of a 32 kd protein. This polypeptide, the "protective protein" was previously shown to be intimately associated with human beta-galactosidase. In addition, the protective protein was found to be essential for the in vivo stability of beta-galactosidase by aggregating beta-galactosidase monomers into high molecular weight multimers. Both chromosome 3 and 22 are therefore necessary to obtain normal levels of beta-galactosidase activity in human cells.
D000818:Animals; D000911:Antibodies, Monoclonal; D002460:Cell Line; D011232:Chemical Precipitation; D002874:Chromosome Mapping; D002900:Chromosomes, Human, 1-3; D002904:Chromosomes, Human, 21-22 and Y; D006224:Cricetinae; D003412:Cricetulus; D005696:Galactosidases / Q000235:genetics*; D005786:Gene Expression Regulation; D005796:Genes; D006801:Humans; D006822:Hybrid Cells; D051379:Mice; D001616:beta-Galactosidase / Q000235:genetics*
D000911:Antibodies, Monoclonal; D005696:Galactosidases; D001616:beta-Galactosidase