Plg (plasminogen), a member of the serine protease superfamily, is a key component constituting the fibrinolytic system, and its evolutionary origin remains unknown during the course of animal evolution. In the present study, we isolated a cDNA, designated BbPlgl, encoding a kringle-containing protease with plasminogen-like activity from the basal chordate Branchiostoma belcheri. The deduced protein, BbPlgl, consisted of 430 amino acids, which is structurally characterized by the presence of an N-terminal signal peptide of 16 amino acids, 2 kringle domains with a Lys-binding site structure, a serine protease domain with the putative tPA (tissue plasminogen activator)-cleavage site (between Arg297 and Val298), the catalytic triad His237-Asp288-Ser379 expected for protease function, and a potential N-linked glycosylation site, all characteristic of Plgs. Besides, the recombinant refolded BbPlgl was readily activated by human uPA (urokinase plasminogen activator), and exhibited Plg-like activity. BbPlgl was also able to auto-activate at neutral and alkaline pH at 4°C without the addition of uPA, and the activation was accelerated by addition of human uPA. These results demonstrate that BbPlgl is a novel member of the Plg family, with a domain structure of K-K-SP (kringle-kringle-serine protease) lacking the PAN domain, pushing the evolutionary origin of Plg to the protochordate. In addition, BbPlgl displays a tissue-specific expression pattern in B. belcheri, with the most abundant expression in the hepatic caecum and hind-gut, agreeing with the notion that the hepatic caecum of amphioxus is the precursor of the vertebrate liver.
Skip Nav Destination
Article navigation
Research Article|
September 02 2009
A kringle-containing protease with plasminogen-like activity in the basal chordate Branchiostoma belcheri
Mingying Liu;
Mingying Liu
1Department of Marine Biology, Ocean University of China, Qingdao 266003, China
Search for other works by this author on:
Shicui Zhang
Shicui Zhang
1
1Department of Marine Biology, Ocean University of China, Qingdao 266003, China
1To whom correspondence should be addressed (email sczhang@ouc.edu.cn).
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
December 03 2008
Revision Received:
January 16 2009
Accepted:
February 04 2009
Accepted Manuscript online:
February 04 2009
Online ISSN: 1573-4935
Print ISSN: 0144-8463
© The Authors Journal compilation © 2009 Biochemical Society
2009
Biosci Rep (2009) 29 (6): 385–395.
Article history
Received:
December 03 2008
Revision Received:
January 16 2009
Accepted:
February 04 2009
Accepted Manuscript online:
February 04 2009
Citation
Mingying Liu, Shicui Zhang; A kringle-containing protease with plasminogen-like activity in the basal chordate Branchiostoma belcheri. Biosci Rep 1 December 2009; 29 (6): 385–395. doi: https://doi.org/10.1042/BSR20080173
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Captcha Validation Error. Please try again.