LIM domain & actin-binding protein 1 (epithelial protein lost in neoplasm, LIMA1, EPLIN, SREBP3, PP624)
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Function
- binds to actin monomers & filaments
- increases number & size of actin stress fibers & inhibits membrane ruffling
- inhibits actin filament depolymerization
- bundles actin filaments, delays filament nucleation & reduces formation of branched filaments
Structure
- contains 1 LIM zinc-binding domain
- contains at least 2 actin-binding domains one on each side of the LIM domain both domains bind actin monomers & filaments the C-terminal domain binds filaments more efficiently than the N-terminus
Compartment
- cytoplasm, cell junction, focal adhesion, cytoskeleton
- co-localizes with actin stress fibers & focal adhesion plaques
Alternative splicing
Expression
- highly expressed in placenta, kidney, pancreas, prostate, ovary, spleen & heart
- also detected in lung, liver, brain, skeletal muscle, thymus, testis & intestine
- not detected in leukocytes
- isoform Beta expressed generally at very low levels, constitutively expressed
- isoform Alpha abundant in epithelial cells from mammary gland, prostate & in normal oral keratinocytes induced by serum.
- low levels in aortic endothelial cells & dermal fibroblasts
- not detectable in myocardium
Pathology
- down-regulated in some cancer cell lines