Several recognition sites for novel sequence-specific DNA-binding proteins were found at the 5'-side of the chicken alpha-globin gene domain in a 1.7 Kbp DNA fragment. This fragment includes the replication origin, a non tissue-specific transcriptional enhancer, a DNAse I hypersensitive site and a permanent site of DNA attachment to the nuclear matrix. Most of the identified protein binding sites differ from previously known consensus sequences. Two sites coincide with MARs located at the 5'-end of the 1.7 kbp fragment. The proteins interacting with these two recognition sites were observed only in proliferating cells and were virtually absent in the extracts obtained from the nonreplicating differentiated form of the same cells. One of them seems to belong to the GATA protein family, but its presence in nuclear extracts correlates with cell proliferation rather than expression of the domain.