A novel human homolog of eosinophil major basic protein

Authors: Plager, D.A.; Adolphson, C.R.; Gleich, G.J.

Source: Immunological Reviews, Volume 179, Number 1, 1 February 2001 , pp. 192-202(11)

Publisher: Wiley-Blackwell

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Abstract:

Summary:

Eosinophil major basic protein (MBP) contributes to host defense and disease pathophysiology. Chromosome 11 contains the genes for human MBP1 (hMBP1) and a second novel MBP, hMBP2, in the centromere to 11q12 region. Interestingly, greater similarity exists between human and murine MBP1 and MBP2 orthologs, respectively, than between hMBP1 and hMBP2, suggesting a gene duplication event prior to the divergence of humans and mice. There is abundant mRNA for hMBP1 in both bone marrow (eosinophils and basophils) and placenta, but hMBP2 mRNA is present only in bone marrow (eosinophils). Comparison of proximal promoters for hMBP2, hMBP1, and murine MBP1 (mMBP1) shows a conserved GATA transcription factor binding site (functionally active in hMBP1). However, whether a C/EBP binding site common to hMBP1 and mMBP1 is functionally conserved in hMBP2 remains unresolved. Similarly, the role of conserved putative IK2 and STAT binding sites in MBP transcriptional control remains unknown. Like hMBP1, hMBP2 is in the eosinophil secondary granule. However, hMBP2 is twofold less positively charged than hMBP1 (+8 versus +16 at neutral pH), and this difference may explain hMBP2's similar, but often less potent, in vitro biological activities. Overall, while conservation of hMBP2's amino acid sequence (63% identity with hMBP1) suggests a common function(s) with hMBP1, hMBP2's substantially reduced charge and the existence of the similar mMBP2 argue for additional, unique functions for hMBP2.

Document Type: Original article

Affiliations: 1: Department of Immunology, Mayo Clinic and Mayo Foundation, Rochester, MN USA.

Publication date: 2001-02-01