Apolipoprotein B is a major protein constituent of chylomicrons (apo B-48), LDL (apo B-100) and VLDL (apo B-100). Apo B-100 functions as a recognition signal for the cellular binding and internalization of LDL particles by the apoB/E receptor. Interacts with PCSK9. Interacts with MTTP. Interacts with AUP1. Palmitoylated; structural requirement for proper assembly of the hydrophobic core of the lipoprotein particle. The stop codon (UAA) at position 2179 is created by RNA editing. Apo B-48, derived from the fully edited RNA, is produced only in the intestine and is found in chylomicrons. Apo B-48 is a shortened form of apo B-100 which lacks the LDL-receptor region. The unedited version (apo B-100) is produced by the liver and is found in the VLDL and LDL (By similarity). Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.