大鼠前α-抑制剂重链与比基尼在COS-1细胞中的细胞内偶联
Intracellular coupling of bikunin and the heavy chain of rat pre-alpha-inhibitor in COS-1 cells.
作者信息
Blom A M, Thuveson M, Fries E
机构信息
Department of Medical and Physiological Chemistry, Uppsala University, Biomedical Center, Sweden.
出版信息
Biochem J. 1997 Nov 15;328 ( Pt 1)(Pt 1):185-91. doi: 10.1042/bj3280185.
Pre-alpha-inhibitor is a serum protein consisting of two polypeptides: bikunin of 16 kDa, which carries an 8 kDa chondroitin sulphate chain, and heavy chain 3 (H3) of 74 kDa. The two polypeptides are linked through an ester bond between an internal N-acetylgalactosamine residue of the chondroitin sulphate chain and the C-terminal aspartic acid residue of H3. Both bikunin and H3 are synthesized by hepatocytes and become linked as they pass through the Golgi complex. H3 is synthesized with both N- and C-terminal extensions which are released during intracellular transport. To be able to analyse the assembly of pre-alpha-inhibitor in detail, we have cloned and sequenced the cDNA of rat H3. Upon expression of the protein in COS-1 cells, both propeptides were found to be released. Furthermore, co-expression of H3 and bikunin resulted in the two polypeptides becoming coupled, indicating that cells other than hepatocytes may have the capacity to form chondroitin sulphate-containing links.
前α抑制剂是一种血清蛋白，由两种多肽组成：16 kDa的比基尼（bikunin），其携带一条8 kDa的硫酸软骨素链，以及74 kDa的重链3（H3）。这两种多肽通过硫酸软骨素链内部的N - 乙酰半乳糖胺残基与H3的C端天冬氨酸残基之间的酯键相连。比基尼和H3均由肝细胞合成，并在通过高尔基体时相连。H3合成时带有N端和C端延伸，在细胞内运输过程中释放。为了能够详细分析前α抑制剂的组装过程，我们克隆并测序了大鼠H3的cDNA。在COS - 1细胞中表达该蛋白时，发现两种前肽均被释放。此外，H3和比基尼的共表达导致这两种多肽结合，表明除肝细胞外的其他细胞可能具有形成含硫酸软骨素连接的能力。
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