Evidence that a single replication fork proceeds from early to late replicating domains in the IgH locus in a non-B cell line
Abstract
In non–B cell lines, like the murine erythroleukemia cell line (MEL), the most distal IgH constant region gene, Ca, replicates early in S; other heavy chain con- stant region genes, joining and diversity segments, and the most proximal Vh gene replicate successively later in S in a 3' to 5' direction proportional to their distance from Ca. In MEL, replication forks detected in the IgH locus also proceed in the same 3' to 5' direction for ~400 kb, beginning downstream of the IgH3' regulatory region and continuing to the Dregion, as well as within the Vh81X gene. Downstream of the initiation region is an early replicating domain, and upstream of Vh81X is a late replicating domain. Hence, the gradual transition between early and late replicated domains can be acheived by a single replication fork.