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91.
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C F Semenkovich C C Luo M K Nakanishi S H Chen L C Smith L Chan 《The Journal of biological chemistry》1990,265(10):5429-5433
Detailed structure-function information about human lipoprotein lipase (LPL) is unavailable because it is difficult to purify large amounts of the enzyme for study. To circumvent this problem, we constructed an in vitro LPL expression vector. Human LPL cDNA was cloned and inserted into the expression vector p91023(B). After transfection of COS M-6 cells with the human LPL cDNA construct, LPL enzyme activity was detected in cell extracts and culture medium. Purified human apolipoprotein C-II caused a 5-fold stimulation of the recombinant human LPL expressed in vitro. Using site-specific mutagenesis, Ala residues were substituted for Asn residues at two potential N-linked glycosylation sites (positions 43 and 359) and at a third unrelated Asn (position 257) in the LPL cDNA. RNA blot analysis demonstrated the presence of a single mRNA species in COS cells transfected with wild-type and mutant LPL expression vectors. Intracellular and secreted LPL activity was absent in the construct containing an Ala for Asn mutation at position 43, whereas the same substitutions at positions 257 and 359 did not appreciably affect activity. LPL activity was also absent in another construct containing a Gln for Asn mutation at position 43. Quantitation of LPL protein mass concomitant with measurement of enzyme activity showed that substitution of Ala or Gln for Asn at position 43 resulted in the production of an enzymatically inactive protein which accumulated intracellularly but was not secreted into the culture medium. Our report represents an initial documentation of the expression of cloned human LPL in vitro and of the importance of Asn-43 for both enzyme activity and secretion. 相似文献
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A subsystem impactor test for pedestrian lower limb injury evaluation has been brought in China New Car Assessment Protocol(CNCAP).Concerning large anthropometr... 相似文献
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Yao Zhou Diyin Li Jianhua Luo Aizhong Chen Xingxing Li Zhenrui Pan Li Wan Liuqing He Danyang Li Yanyan Li Min Dong Liang Tao 《Cell research》2021,31(8):935-938
Dear Editor,
Clostridium novyi(C.novyi)is a spore-forming anaerobic bacterium and opportunistic pathogen causing severe infectious diseases in humans and animal... 相似文献
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Fei Huang Puiian Wong Jinglan Li Zheng Lv Liangliang Xu Genfu Zhu Mincong He Yiwen Luo 《Journal of cellular and molecular medicine》2022,26(13):3591
Osteoporosis is a bone disease that is caused by disorder of the skeletal microenvironment, and it characterized by a high disability rate and the occurrence of low energy fractures. Studies on osteoporosis and related treatment options have always been hot spots in the field of bone biology. In the past, the understanding of osteoporosis has been rather limited; research has only shown that osteoporosis involves the imbalance of bone resorption and bone formation, and recent studies have not provided cutting‐edge theories of the basic understanding of osteoporosis. Recent studies have shown crosstalk between bone and immune responses. RANKL, an essential factor for osteoclasts (OCs), is associated with the immune system. T helper (Th17)/regulatory T (Treg) cells are two different kinds of T cells that can self‐interact and regulate the differentiation and formation of OCs. Therefore, understanding the correlation between the skeletal and immune systems and further revealing the roles and the cooperation between RANKL and the Th17/Treg balance will help to provide new insights for the treatment of osteoporosis. 相似文献