This mitochondrial matrix protein family contains members of the MAM33 family which bind to the globular 'heads' of C1Q. It is thought to be involved in mitochondrial oxidative phosphorylation and in nucleus-mitochondrion interactions [1].

1: Crystal structure of human p32, a doughnut-shaped acidic mitochondrial matrix protein. Jiang J, Zhang Y, Krainer AR, Xu RM; Proc Natl Acad Sci U S A 1999;96:3572-3577. PMID:10097078

2: Mam33p, an oligomeric, acidic protein in the mitochondrial matrix of Saccharomyces cerevisiae is related to the human complement receptor gC1q-R. Seytter T, Lottspeich F, Neupert W, Schwarz E; Yeast 1998;14:303-310. PMID:9559539