ATP-binding cassette sub-family A member 7 (macrophage ABC transporter, autoantigen SS-N, ABCA-SSN, ABCA7)
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Function
- role in phagocytosis by macrophages of apoptotic cells
- binds APOA1
- role in apolipoprotein-mediated phospholipid efflux from cells
- role in cholesterol efflux
- regulates cellular ceramide homeostasis during keratinocyte differentiation (putative)
Structure
- belongs to the ABC transporter family, ABCA subfamily
- contains 2 ABC transporter domains
Compartment
- cell membrane, Golgi membrane, endosomal membrane
- localizes to cell membrane ruffles & phagocytic cups of macrophages stimulated with C1q or apoptotic cells
- localizes to the cytoplasm of resting macrophages, probably in Golgi & endosomes
- localizes to the apical brush border of cells in proximal tubules of kidney
- isoform 2 may localize to endoplasmic reticulum
Alternative splicing
named isoforms=2
Expression
- widely expressed
- expressed in myelo-lymphatic tissues including peripheral leukocytes, thymus, spleen, bone marrow
- isoform 2 is more abundant in lymph node, spleen, thymus & trachea than isoform 1
- isoform 1 which is more abundant in brain & bone marrow than isoform 2
- expressed in fetal tissues, with strong expression in fetal liver.
- up-regulated in macrophages upon cholesterol uptake
- inversely regulated upon cholesterol deloading from cells
- up-regulated in keratinocytes during terminal differentiation