A PEST sequence in ABCA1 regulates degradation by calpain protease and stabilization of ABCA1 by apoA-I
J. Clin. Invest. Nan Wang, et al. 111:99 doi:10.1172/JCI16808 [
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Figure 1A PEST sequence regulates the cell surface expression and function of ABCA1. (
a) Schematic model of ABCA1 showing the location and amino acid sequence of the PEST sequence in mouse (m), human (h), and chicken (c). The PEST score is +16.42, as determined by PESTfind. (
b) Levels of total (bottom) and cell surface (top, biotinylated) ABCA1 and ABCA1delPEST in transiently transfected HEK293 cells. (
c,
f, and
g) DNA dose-dependent ABCA1-mediated and ABCA1delPEST-mediated cellular cholesterol efflux (
c), phospholipid efflux (
f), and apoA-I cell association (
g). (
d) Total cellular ABCA1 protein mass as determined by quantitative Western blotting in the cholesterol efflux assay. (
e) Cholesterol efflux efficiency determined by percentage efflux normalized for total cellular ABCA1 protein mass. (
h) Levels of total (bottom) and ubiquitinated (top) ABCA1 and ABCA1delPEST in HEK293 cells incubated with or without lactacystin (20 μM) for 3 hours. The data are representative of two experiments (
c and
e–
h, triplicate;
d, duplicate) or three experiments (
b, duplicate and triplicate) with similar results.
