Abstract
Lipoprotein lipase (LPL), the enzyme that hydrolyzes triglycerides in plasma lipoproteins, is assumed to be active only as a homodimer. In support of this idea, several groups have reported that the size of LPL, as measured by density gradient ultracentrifugation, is ∼110 kDa, twice the size of LPL monomers (∼55 kDa). Of note, however, in those studies the LPL had been incubated with heparin, a polyanionic substance that binds and stabilizes LPL. Here we revisited the assumption that LPL is active only as a homodimer. When freshly secreted human LPL (or purified preparations of LPL) was subjected to density gradient ultracentrifugation (in the absence of heparin), LPL mass and activity peaks exhibited the size expected of monomers (near the 66-kDa albumin standard). GPIHBP1-bound LPL also exhibited the size expected for a monomer. In the presence of heparin, LPL size increased, overlapping with a 97.2-kDa standard. We also used density gradient ultracentrifugation to characterize the LPL within the high-salt and low-salt peaks from a heparin- Sepharose column. The catalytically active LPL within the high-salt peak exhibited the size of monomers, whereas most of the inactive LPL in the low-salt peak was at the bottom of the tube (in aggregates). Consistent with those findings, the LPL in the low-salt peak, but not that in the high-salt peak, was easily detectable with single mAb sandwich ELISAs, in which LPL is captured and detected with the same antibody. We conclude that catalytically active LPL can exist in a monomeric state.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 6319-6328 |
| Number of pages | 10 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 116 |
| Issue number | 13 |
| DOIs | |
| State | Published - Jan 1 2019 |
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Keywords
- Lipase
- Lipolysis
- Triglycerides
ASJC Scopus subject areas
- General
Cite this
Lipoprotein lipase is active as a monomer. / Beigneux, Anne P.; Allan, Christopher M.; Sandoval, Norma P.; Cho, Geoffrey W.; Heizer, Patrick J.; Jung, Rachel S.; Stanhope, Kimber; Havel, Peter J; Birrane, Gabriel; Meiyappan, Muthuraman; Gill Iv, John E.; Murakami, Masami; Miyashita, Kazuya; Nakajima, Katsuyuki; Ploug, Michael; Fong, Loren G.; Young, Stephen G.
In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 116, No. 13, 01.01.2019, p. 6319-6328.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Lipoprotein lipase is active as a monomer
AU - Beigneux, Anne P.
AU - Allan, Christopher M.
AU - Sandoval, Norma P.
AU - Cho, Geoffrey W.
AU - Heizer, Patrick J.
AU - Jung, Rachel S.
AU - Stanhope, Kimber
AU - Havel, Peter J
AU - Birrane, Gabriel
AU - Meiyappan, Muthuraman
AU - Gill Iv, John E.
AU - Murakami, Masami
AU - Miyashita, Kazuya
AU - Nakajima, Katsuyuki
AU - Ploug, Michael
AU - Fong, Loren G.
AU - Young, Stephen G.
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Lipoprotein lipase (LPL), the enzyme that hydrolyzes triglycerides in plasma lipoproteins, is assumed to be active only as a homodimer. In support of this idea, several groups have reported that the size of LPL, as measured by density gradient ultracentrifugation, is ∼110 kDa, twice the size of LPL monomers (∼55 kDa). Of note, however, in those studies the LPL had been incubated with heparin, a polyanionic substance that binds and stabilizes LPL. Here we revisited the assumption that LPL is active only as a homodimer. When freshly secreted human LPL (or purified preparations of LPL) was subjected to density gradient ultracentrifugation (in the absence of heparin), LPL mass and activity peaks exhibited the size expected of monomers (near the 66-kDa albumin standard). GPIHBP1-bound LPL also exhibited the size expected for a monomer. In the presence of heparin, LPL size increased, overlapping with a 97.2-kDa standard. We also used density gradient ultracentrifugation to characterize the LPL within the high-salt and low-salt peaks from a heparin- Sepharose column. The catalytically active LPL within the high-salt peak exhibited the size of monomers, whereas most of the inactive LPL in the low-salt peak was at the bottom of the tube (in aggregates). Consistent with those findings, the LPL in the low-salt peak, but not that in the high-salt peak, was easily detectable with single mAb sandwich ELISAs, in which LPL is captured and detected with the same antibody. We conclude that catalytically active LPL can exist in a monomeric state.
AB - Lipoprotein lipase (LPL), the enzyme that hydrolyzes triglycerides in plasma lipoproteins, is assumed to be active only as a homodimer. In support of this idea, several groups have reported that the size of LPL, as measured by density gradient ultracentrifugation, is ∼110 kDa, twice the size of LPL monomers (∼55 kDa). Of note, however, in those studies the LPL had been incubated with heparin, a polyanionic substance that binds and stabilizes LPL. Here we revisited the assumption that LPL is active only as a homodimer. When freshly secreted human LPL (or purified preparations of LPL) was subjected to density gradient ultracentrifugation (in the absence of heparin), LPL mass and activity peaks exhibited the size expected of monomers (near the 66-kDa albumin standard). GPIHBP1-bound LPL also exhibited the size expected for a monomer. In the presence of heparin, LPL size increased, overlapping with a 97.2-kDa standard. We also used density gradient ultracentrifugation to characterize the LPL within the high-salt and low-salt peaks from a heparin- Sepharose column. The catalytically active LPL within the high-salt peak exhibited the size of monomers, whereas most of the inactive LPL in the low-salt peak was at the bottom of the tube (in aggregates). Consistent with those findings, the LPL in the low-salt peak, but not that in the high-salt peak, was easily detectable with single mAb sandwich ELISAs, in which LPL is captured and detected with the same antibody. We conclude that catalytically active LPL can exist in a monomeric state.
KW - Lipase
KW - Lipolysis
KW - Triglycerides
UR - http://www.scopus.com/inward/record.url?scp=85063936170&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85063936170&partnerID=8YFLogxK
U2 - 10.1073/pnas.1900983116
DO - 10.1073/pnas.1900983116
M3 - Article
C2 - 30850549
AN - SCOPUS:85063936170
VL - 116
SP - 6319
EP - 6328
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 13
ER -