Abstract
The susceptibility of three different solubilized forms of type IV collagen to gelatinase A cleavage and the concomitant effects on cell and integrin binding have been assessed. Dithiothreitol-solubilized Engelbreth-Holm Swarm (EHS) type IV collagen with disrupted intramolecular disulfide bonds in the CB3[IV] region was cleaved N-terminally to the CB3[IV] region into the two characteristic 100-300-nm fragments at 30 degrees C and was totally degraded at 37 degrees C. This was reflected in the partial or total loss of the alpha1beta1 and alpha2beta1 integrin binding sites within this region. The ability of gelatinase A to cleave EHS type IV collagen preparations with intact interchain disulfide bonds in CB3[IV] only occurred at higher temperatures. Furthermore, no effect on binding of cells or isolated integrins to the gelatinase-treated collagen could be detected after treatment at 37 degrees C. Dimeric collagen IV of human placenta with intact disulfide bonds in the CB3[IV] region was not degraded at all by gelatinase A at 37 degrees C.
Highlights
The macromolecular organization as well as the biomechanical stability of basement membranes is mainly determined by the network of type IV collagen [1]
Collagen IV Preparations—Monomeric collagen IV molecules were isolated from the murine EngelbrethHolm Swarm (EHS) tumor [22]
It is the only segment of the triple-helical domain that is stabilized by intramolecular disulfide bonds, and it contains the recognition sites for the integrins ␣11 and ␣21 [2]
Summary
The macromolecular organization as well as the biomechanical stability of basement membranes is mainly determined by the network of type IV collagen [1]. The molecules of the major isoform of collagen IV, consisting of two ␣1(IV) chains and one ␣2(IV) chain, are 400 nm long and bear a globular domain at the C terminus [2, 3] They are present in all basement membranes in the form of a network, in which the molecules aggregate with their like ends [4] and interact laterally with the triple-helical domains [5]. The recognition sites for ␣11 and ␣21 within collagen IV have been located in the immediate vicinity of the gelatinase A cleavage site, about 100 nm from the N terminus of the molecules This region is stabilized by intramolecular disulfide bonds between the three ␣(IV) chains and can be isolated as a triple-helical cyanogen bromide fragment, CB3[IV], allowing detailed studies of the structure of the conformation dependent recognition sites [2, 20, 21]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
