The regulatory element 3' to the (A)γ-globin gene binds to the nuclear matrix and interacts with special A-T-rich binding protein 1 (SATB1), an SAR/MAR-associating region DNA binding protein

J. M. Cunningham, M. E. Purucker, S. M. Jane, B. Safer, E. F. Vanin, P. A. Ney, C. H. Lowrey, A. W. Nienhuis

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A cis-acting DNA regulatory element 3' to the (A)γ-globin gene contains eight distinct regions of DNA-protein interaction distributed over 750 bp of DNA. The sequences of two foot-printed regions (sites I and IV) are A-T rich and generate a highly retarded complex on gel shift analysis with nuclear extract from human erythroleukemia (K562) cells. We have purified a 98-kD protein that reproduces this gel shift. Tryptic cleavage and peptide sequence analysis demonstrated that the 98-kD protein is identical to a recently cloned protein, special A-T-rich binding protein 1 (SATB1), that binds selectively to nuclear matrix/scaffold-associated regions of DNA (MARs/SARs). We have shown by functional analysis that the 3' (A)γ regulatory element associates with the nuclear matrix. SATB1 mRNA was identified in K562 cells, and reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated its transcript in several other hematopoietic lines. Antisera to SATB1 caused ablation of the gel shift complex generated by both the crude nuclear extract and the purified 98-kD protein with the site I oligonucleotide. Furthermore, oligonucleotides that bind SATB1 inhibited formation of the site I gel shift complex when added as excess unlabeled competitor. An immunoblot analysis of the site I gel shift complex documented the presence of SATB1. Binding of SATB1 to two sites within the 3' (A)γ regulatory element and its MAR/SAR activity suggests that this element may influence gene expression through interaction with the nuclear matrix.

Original languageEnglish
Pages (from-to)1298-1308
Number of pages11
Issue number4
Publication statusPublished - 1 Jan 1994
Externally publishedYes

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