ISSN:
0730-2312
Keywords:
tissue-plasminogen activator
;
α2-antiplasmin
;
protein glycosylation
;
miniplasminogen
;
streptokinase
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
The human [Glu1]-plasminogen carbohydrate isozymes, plasminogen type I (Pg 1) and plasminogen type II (Pg 2), were separated by chromatography and studied in cell binding experiments at 4°C with primary cultures of rat hepatocytes and rat C6 glioma cells. In both cell systems, Pg 1 and Pg 2 bound to an equivalent number of receptors, apparently representing the same population of surface molecules The affinity for Pg 2 was slightly higher. With hepatocytes, the KD for Pg 1 was 3.2 ± 0.2 μM, and the KD for Pg 2 was 1.9 ± 0.1 μM, as determined from Scatchard transformations of the binding isotherms. The Bmax was approximately the same for both isozymes. With C6 cells, the KD for Pg 1 was 2.2 ± 0.1 μM vs. 1.5 ± 0.2 μM for Pg 2. Again, the Bmax was similar with both isozymes. 125I-Pg 1 and 125I -Pg 2 were displaced from specific binding sites by either nonradiolabeled isozyme. The KI for Pg 2 was slightly lower than the KI for Pg 1 with hepatocytes (0.9 vs. 1.3 μM) and with C6 cells (0.6 vs. 1.1 μM). No displacement was detected with miniplasminogen at concentrations up to 5.0 μM. Activation of Pg 1 and Pg 2 by recombinant two-chain tissue-plasminogen activator (rt-PA) was enhanced by hepatocyte cultures. The enhancing effect was greater with Pg 2. Hepatocyte cultures did not affect the activation of miniplasminogen by rt-PA or the activation of plasminogen by streptokinase. Unlike the hepatocytes, C6 cells did not enhance the activation of plasminogen by rt-PA or streptokinase; however, plasmin generated in the presence of C6 cells reacted less readily with α2 -antiplasmin.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcb.240430303
Permalink
