Drosophila Claspin is required for the G2 arrest that is induced by DNA replication stress but not by DNA double-strand breaks.

ATR and Chk1 are protein kinases that perform major roles in the DNA replication checkpoint that delays entry into mitosis in response to DNA replication stress by hydroxyurea (HU) treatment. They are also activated by ionizing radiation (IR) that induces DNA double-strand breaks. Studies in human tissue culture and Xenopus egg extracts identified Claspin as a mediator that increased the activity of ATR toward Chk1.

Functional analysis of mutations in UDP-galactose-4-epimerase (GALE) associated with galactosemia in Korean patients using mammalian GALE-null cells.

Galactosemia is caused by defects in the galactose metabolic pathway, which consists of three enzymes, including UDP-galactose-4-epimerase (GALE). We previously reported nine mutations in Korean patients with epimerase-deficiency galactosemia. In order to determine the functional consequences of these mutations, we expressed wild-type and mutant GALE proteins in 293T cells.