GENETIC-DIFFERENCES BETWEEN THE PANCYTOSOLIC AND PERINUCLEAR FORMS OFMURINE MORTALIN

To determine the genetic relation between the pancytosolic (uniformly distributed in cytoplasm-p66(mot-1)) and the perinuclear (p66(mot-2)) mortalin proteins found in normal and immortal mouse cells, respective ly, we initiated the present study using PCR cloning, sequencing, and single nucleotide primer extension analyses, The results indicate that the difference between mot-1 and mot-2 at 2 bp in the open reading fr ame does not arise by mutations in the immortalized cells, Intriguingl y, both mot-1 and mot-2 sequences were detected in genomic DNA from no rmal (CMEF) and immortal (RS-4) cells derived from the CDI-ICR mouse s train. We extended the analyses to four other strains of mouse and det ected both mot-1 and mot-2 sequences in genomic DNA from the Balb/c mo use also. Swiss and C57BL/6 mice exhibited only mot-2 and the C3H He m ouse only mot-1. Southern analyses on a mouse strain that showed the p resence of only mot-2 (Swiss) and one that showed both mot-1 and mot-2 (CD1-ICR) by PCR revealed that there are structural differences betwe en mot-1 and mot-2 loci, Furthermore, there appears to be a correlatio n between frequency of spontaneous immortalization of cultured mouse f ibroblasts and the mot loci present in the mouse strain from which the y were derived. (C) 1996 Academic Press, Inc.