apolipoprotein B

Function

• major protein constituent of chylomicrons (apo B-48), LDL (apo B-100) & VLDL (apo B-100)
• apo B-100 functions as a recognition signal for the cellular binding & internalization of LDL particles by the apoB/E receptor (LDL receptor)

Structure

• palmitoylated structural requirement for proper assembly of the hydrophobic core of the lipoprotein particle
• contains 1 vitellogenin domain

Compartment

secreted

RNA editing

• modified positions=2180
  • the stop codon (UAA) at position 2180 is created by RNA editing
  • apo B-48, derived from the fully edited RNA, is produced only in the intestine & is found in chylomicrons
  • apo B-48 is a shortened form of apo B-100 which lacks the LDL-receptor region

Expression

• liver (apo B-100); intestine (apo B-48)
• up-regulated in response to enterovirus 71 (EV71) infection (at protein level)

Pathology

• defects in APOB are a cause of
  • familial hypobetalipoproteinemia type 1
  • familial ligand-defective apolipoprotein B-100
• defects in APOB associated with defects in other genes (polygenic) can contribute to hypocholesterolemia

* see ARUP consult

More general terms

• apolipoprotein
• beta globulin
• phosphoprotein

More specific terms

• apolipoprotein B100 (apoB100)
• apolipoprotein B48 (apoB48)

Additional terms

• apolipoprotein A1/B in serum

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=338
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:338
• OMIM: https://mirror.omim.org/entry/107730
• OMIM: https://mirror.omim.org/entry/144010
• UniProt: http://www.uniprot.org/uniprot/P04114.html