Recombinant Human CCL23/MPIF-1 Protein

Myeloid progenitor inhibitory factor (MPIF-1), also known as CK beta8 and MIP-3, is a member of the CC chemokine subfamily that is designated CCL23. Alternative splicing of the MPIF-1 gene results in two mRNAs that encode a short (CK beta8) and a long (CK beta8-1) isoform of the chemokine. CK beta8 cDNA encodes a 120 amino acid (aa) residue precursor protein with a putative 21 aa residue signal peptide that is cleaved to generate a 99 aa residue mature CK beta8 (aa 22 - 120). Additional N-terminal processing of the 99 aa residue variant can generate a 75 aa residue CK beta8 (aa 46 - 120) that is significantly more active than the 99 aa residue variant. Similarly, CK beta8-1 encodes a 137 aa residue precursor protein that can give rise to a 116 and a 92 aa residue chemokine. Among CC chemokine members, MPIF-1 is most closely related to MIP-5/CCL15 (67% sequence identity) and MIP-1 alpha/CCL3 (51%). MPIF-1 mRNA is most abundant in the adult lung and liver, but is also present in bone marrow, placenta, and various myelomonocytic cell lines. MPIF-1 has been shown to suppress the low proliferative potential colony-forming cells that give rise to granulocyte and monocyte lineages. MPIF-1 binds to CCR1 with high affinity and has been shown to be a potent chemoattractant and activator of monocytes, dendritic cells, and osteoclast precursors.