Using gene targeting in embryonic stem cells, we have derived mice with a null mutation in a DNA mismatch repair gene homolog, PMS2. We observed microsatellite instability in the male germline, in tail, and in tumor DNA of PMS2-deficient animals. We therefore conclude that PMS2 is involved in DNA mismatch repair in a variety of tissues. PMS2-deficient… (More)
Using a cell-free system we have obtained fusion of vesicles from the endocytic pathway. The fusion is rapid, efficient, and requires ATP. Only vesicles derived from certain positions along the endocytic pathway are capable of fusing. Lysosomes and vesicles derived from the plasma membrane do not fuse.