LDLRAP1 is a cytosolic protein which contains a phosphotyrosine binding (PTD) domain. The PTD domain has been found to interact with the cytoplasmic tail of the LDL receptor. This adapter protein is required for efficient endocytosis of the LDL receptor (LDLR) in polarized cells such as hepatocytes and lymphocytes, but not in non-polarized cells (fibroblasts). LDLRAP1 may be required for LDL binding and internalization but not for receptor clustering in coated pits. This protein may facilitate the endocytocis of LDLR and LDLR-LDL complexes from coated pits by stabilizing the interaction between the receptor and the structural components of the pits, and may also be involved in the internalization of other LDLR family members. Mutations in the LDLRAP1 gene lead to LDL receptor malfunction and cause the disorder autosomal recessive hypercholesterolaemia.

HUMAN

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