Amita Mishra1, Bal Krishnan1, Rajeev Raman1, Yogendra Sharma2. 1. CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500 007, India. 2. CSIR-Centre for Cellular and Molecular Biology (CCMB), Uppal Road, Hyderabad 500 007, India. Electronic address: yogendra@ccmb.res.in.
Abstract
BACKGROUND: During the last three decades, lens β- and γ-crystallins have found a huge number of kin from numerous taxonomical sources. Most of these proteins from invertebrates and microbes have been demonstrated or predicted to bind Ca2+ involving a distinct double-clamp motif, which is largely degenerated in lens homologues. SCOPE OF REVIEW: The various aspects of transformation of βγ-crystallins from a quintessential Ca2+-binding protein into a primarily structural molecule have been reviewed. MAJOR CONCLUSIONS: In lens members of βγ-crystallins, the residues involved in Ca2+ binding have diverged considerably from the classical consensus with consequent reduction in their Ca2+-binding properties. This evolutionary change is congenial to their new role as robust constituents of lens. The exact functions of the residual affinity for Ca2+ are yet to be established. GENERAL SIGNIFICANCE: This review highlights the significance of reduction in Ca2+-binding ability of the βγ-crystallins for lens physiology and why this residual affinity may be functionally important. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
BACKGROUND: During the last three decades, lens β- and γ-crystallins have found a huge number of kin from numerous taxonomical sources. Most of these proteins from invertebrates and microbes have been demonstrated or predicted to bind Ca2+ involving a distinct double-clamp motif, which is largely degenerated in lens homologues. SCOPE OF REVIEW: The various aspects of transformation of βγ-crystallins from a quintessential Ca2+-binding protein into a primarily structural molecule have been reviewed. MAJOR CONCLUSIONS: In lens members of βγ-crystallins, the residues involved in Ca2+ binding have diverged considerably from the classical consensus with consequent reduction in their Ca2+-binding properties. This evolutionary change is congenial to their new role as robust constituents of lens. The exact functions of the residual affinity for Ca2+ are yet to be established. GENERAL SIGNIFICANCE: This review highlights the significance of reduction in Ca2+-binding ability of the βγ-crystallins for lens physiology and why this residual affinity may be functionally important. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Authors: Megan A Rocha; Marc A Sprague-Piercy; Ashley O Kwok; Kyle W Roskamp; Rachel W Martin Journal: Chembiochem Date: 2021-02-10 Impact factor: 3.164