Potential proteolytic activity of human plasma fibronectin: fibronectin gelatinase.
Human plasma fibronectin contains a latent proteinase that after activation cleaves gelatin and fibronectin. The autoactivation propensity of the two purified cathepsin D-produced fragments of fibronectin (190 and 120 kDa) was compared. Both polypeptides were spontaneously activated in the presence of Ca2+. This activation was inhibited by EDTA. The active gelatinase was isolated from the autodigest of the 190-kDa fragment. Among various protein substrates, including laminin and native type I and IV collagens, the purified enzyme degraded only gelatin and fibronectin. We have named this proteinase FN-gelatinase. FN-gelatinase is inhibited by phenylmethanesulfonyl fluoride and also by pepstatin A like retroviral aspartic proteinases. The amino-acid composition of the purified enzyme (35 kDa) was compared with the entire fibronectin sequence using the computer programme FIT. The optimal fit indicated that the 35-kDa fragment corresponds to the stretch # 1043-1404. This sequence contains a 93-residue segment (# 1140-1233) analogous to retroviral aspartic proteinases, comprising the sequence DTG of their putative active site.
Planchenault
T
T
Unité de Chimie des Protéines, Institut Pasteur, Paris.
Lambert Vidmar
S
S
Imhoff
J M
JM
Blondeau
X
X
Emod
I
I
Lottspeich
F
F
Keil-Dlouha
V
V
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis*; D003094:Collagen / Q000378:metabolism; D010450:Endopeptidases / Q000097:blood / Q000302:isolation & purification*; D004789:Enzyme Activation; D005353:Fibronectins / Q000032:analysis*; D005780:Gelatin / Q000378:metabolism*; D018093:Gelatinases; D006801:Humans; D008969:Molecular Sequence Data; D010434:Pepsin A / Q000097:blood / Q000302:isolation & purification*; D010446:Peptide Fragments / Q000032:analysis*; D011480:Protease Inhibitors; D012190:Retroviridae / Q000201:enzymology; D013379:Substrate Specificity
D000596:Amino Acids; D005353:Fibronectins; D010446:Peptide Fragments; D011480:Protease Inhibitors; D005780:Gelatin; D003094:Collagen; D010450:Endopeptidases; D010434:Pepsin A; D018093:Gelatinases; C064016:fibronectin laminase