C1QBP

C1QBP is 282 amino acid in length and has three homologous subunit with its N-terminal 73 amino acid residues cleaved off to produce mature C1QBP. C1QBP appears as a monomer around 33 kDa on SDS-PAGE gel under both reducing and nonreducing condition but migrates as a trimer on size-exclusion chromatography (gel filtration).[8]

The crystal structure of C1QBP at 2.25 Å resolution shows a homotrimeric ring displaying symmetry. The individual subunits are held together by noncovalent interactions and forms a doughnut shaped quaternary structure with a central cavity of 20 Å in diameter. Each Subunit of C1QBP has seven β-strand (β1- β7) and three α-helices (α1- α3). C1QBP is negatively charged on its soluble face while the membrane face is predominantly positively charged.[9]

C1QBP has been shown to interact with Protein kinase D1,[10] BAT2,[11] PRKCD,[10] PKC alpha[10] and Protein kinase Mζ.[10] Other interacting partners of C1QBP include protein domains from pathogens such as bacteria,[12] virus [13] and plasmodium falciparum.[14] Plasma proteins including fibrinogen, FXII and HK have been demonstrated to interact with C1QBP in a zinc dependent manner,.[15][16] Recently, a tumour homing peptide, LyP-1(CGNKRTRGC) has been shown to selectively bind to C1QBP in tumour expressing cells.[17]

• Human C1QBP genome location and C1QBP gene details page in the UCSC Genome Browser.