An Insoluble Structural Glycoprotein a Major Constituent of the Zonula Zinni

¹ Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, N. Y., 10032

Experiments were carried out to determine the localization of the insoluble structural glycoprotein ivhich remains after exhaustive degradation of the bovine and rabbit lens capsules with high-purity collagenase. The material can be extracted from the residue with 0.1 M -mercaptoethanol at room temperature. Most of this material was shown to be present in the capsule of the equatorial region of the lens. Furthermore, preparations of lens capsule containing the extracapsular^* fibrils of zonula Zinni were shown to contain about as much of this structural glycoprotein as the whole capsule itself. The glycoprotein appears to be a major constituent of the zonula fibrils and the compositibn of its carbohydrate suggests a close relationship to the glycoprotein of the vitreous body previously obtained in our laboratory as an insoluble precipitate after degradation of the hyaluronic acid of the vitreous.