Pathway candidateNCBI-verifiedprotein-coding

NPC1L1

NPC1 like intracellular cholesterol transporter 1

NCBI Gene: 29881 Ensembl GeneCards UniProt: Q9UHC9

Pathway candidate — not linked to PFS or PSSD by any record here

NPC1L1 is in the library because it belongs to the lipid homeostasis family. No study, report or commentary in the corpus names it, so a variant in NPC1L1 is not, by itself, evidence of anything related to post-drug syndromes.

Gene summary

A protein-coding gene on chromosome 7 (lipid and cholesterol homeostasis). The protein encoded by this gene is a multi-pass membrane protein. It contains a conserved N-terminal Niemann-Pick C1 (NPC1) domain and a putative sterol-sensing domain (SSD) which includes a YQRL motif functioning as a plasma membrane to trans-Golgi network transport signal in other proteins.

Source: NCBI Gene, accessed 2026-10-07.

Protein reference (UniProt)

Protein: NPC1-like intracellular cholesterol transporter 1
Function: Plays a major role in cholesterol homeostasis. Critical for the uptake of cholesterol across the plasma membrane of the intestinal enterocyte. Involved in plant sterol absorption, it transports sitosterol, although at lower rates than cholesterol (By similarity). Is the direct molecular target of ezetimibe, a drug that inhibits cholesterol absorption and is approved for the treatment of hypercholesterolemia. May have a function in the transport of multiple lipids and their homeostasis, thereby influencing lipid metabolism regulation. May be involved in caveolin trafficking from the plasma membrane (By similarity). In addition, acts as a negative regulator of NPC2 and down-regulates its expression and secretion by inhibiting its maturation and accelerating its degradation.
Subcellular location: Apical cell membrane; Cell membrane; Cytoplasmic vesicle membrane.
Tissue specificity: Widely expressed. Expressed in liver. Also expressed in small intestine, pancreas, kidney, lung, pancreas, spleen, heart, gall bladder, brain, testis, stomach and muscle.

Source: UniProtKB/Swiss-Prot Q9UHC9, release 2026_03, licensed CC BY 4.0. This is the protein’s normal biology, not evidence about post-drug syndromes; associated conditions are inherited disorders of the gene, not PFS, PSSD or PRSD.

Why its pathway is in the library

Cholesterol is the obligate precursor of all steroid hormones; lipid handling sets substrate supply for steroidogenesis and neurosteroid synthesis.

Written for the whole lipid homeostasis family, not for NPC1L1 specifically.

Mentioned in 0 corpus records

No corpus record names NPC1L1 directly yet. It is in the library because it sits in a pathway the corpus tracks (Lipid homeostasis).

Also in lipid and cholesterol homeostasis

All 19 genes

Browse by family on the gene families page.

Gene summary

Source: NCBI Gene, accessed 2026-10-07.

Protein reference (UniProt)

Protein: NPC1-like intracellular cholesterol transporter 1
Function: Plays a major role in cholesterol homeostasis. Critical for the uptake of cholesterol across the plasma membrane of the intestinal enterocyte. Involved in plant sterol absorption, it transports sitosterol, although at lower rates than cholesterol (By similarity). Is the direct molecular target of ezetimibe, a drug that inhibits cholesterol absorption and is approved for the treatment of hypercholesterolemia. May have a function in the transport of multiple lipids and their homeostasis, thereby influencing lipid metabolism regulation. May be involved in caveolin trafficking from the plasma membrane (By similarity). In addition, acts as a negative regulator of NPC2 and down-regulates its expression and secretion by inhibiting its maturation and accelerating its degradation.
Subcellular location: Apical cell membrane; Cell membrane; Cytoplasmic vesicle membrane.
Tissue specificity: Widely expressed. Expressed in liver. Also expressed in small intestine, pancreas, kidney, lung, pancreas, spleen, heart, gall bladder, brain, testis, stomach and muscle.