Component of the cytosolic iron-sulfur (Fe-S) protein assembly (CIA) machinery required for the maturation of extramitochondrial Fe-S proteins. Part of an electron transfer chain functioning in an early step of cytosolic Fe-S biogenesis, facilitating the de novo assembly of a [4Fe-4S] cluster on the scaffold complex NUBP1-NUBP2. Electrons are transferred to CIAPIN1 from NADPH via the FAD- and FMN-containing protein NDOR1. NDOR1-CIAPIN1 are also required for the assembly of the diferric tyrosyl radical cofactor of ribonucleotide reductase (RNR), probably by providing electrons for reduction during radical cofactor maturation in the catalytic small subunit. Has anti-apoptotic effects in the cell. Involved in negative control of cell death upon cytokine withdrawal. Promotes development of hematopoietic cells. Monomer. Interacts with ndor1. Interacts with chchd4. The twin Cx2C motifs are involved in the recognition by the mitochondrial CHCHD4/MIA40-GFER/ERV1 disulfide relay system. The formation of 2 disulfide bonds in the Cx2C motifs through dithiol/disulfide exchange reactions effectively traps the protein in the mitochondrial intermembrane space. The C-terminal domain binds 2 Fe-S clusters but is otherwise mostly in an intrinsically disordered conformation. The N-terminal domain has structural similarity with S-adenosyl-L-methionine-dependent methyltransferases, but does not bind S-adenosyl-L-methionine. It is required for correct assembly of the 2 Fe-S clusters. Belongs to the anamorsin family.