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Journal article
Activation of Retinal Guanylyl Cyclase-1 by Ca2+-binding Proteins Involves Its Dimerization
The Journal of biological chemistry, v 274(22), pp 15547-15555
28 May 1999
PMID: 10336449
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Abstract
Retinal guanylyl cyclase-1 (retGC-1), a key enzyme in phototransduction, is activated by guanylyl cyclase-activating proteins (GCAPs) if [Ca2+] is less than 300 nm. The activation is believed to be essential for the recovery of photoreceptors to the dark state; however, the molecular mechanism of the activation is unknown. Here, we report that dimerization of retGC-1 is involved in its activation by GCAPs. The GC activity and the formation of a 210-kDa cross-linked product of retGC-1 were monitored in bovine rod outer segment homogenates, GCAPs-free bovine rod outer segment membranes and recombinant bovine retGC-1 expressed in COS-7 cells. In addition to recombinant bovine GCAPs, constitutively active mutants of GCAPs that activate retGC-1 in a [Ca2+]-independent manner and bovine brain S100b that activates retGC-1 in the presence of ∼10 μm [Ca2+] were used to investigate whether these activations take place through a similar mechanism, and whether [Ca2+] is directly involved in the dimerization. We found that a monomeric form of retGC-1 (∼110 kDa) was mainly observed whenever GC activity was at basal or low levels. However, the 210-kDa product was increased whenever the GC activity was stimulated by any Ca2+-binding proteins used. We also found that [Ca2+] did not directly regulate the formation of the 210-kDa product. The 210-kDa product was detected in a purified GC preparation and did not contain GCAPs even when the formation of the 210-kDa product was stimulated by GCAPs. These data strongly suggest that the 210-kDa cross-linked product is a homodimer of retGC-1. We conclude that inactive retGC-1 is predominantly a monomeric form, and that dimerization of retGC-1 may be an essential step for its activation by active forms of GCAPs.
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Details
- Title
- Activation of Retinal Guanylyl Cyclase-1 by Ca2+-binding Proteins Involves Its Dimerization
- Creators
- Hao Yu - Kresge Eye InstituteElena Olshevskaya - Kresge Eye InstituteTeresa Duda - Rutgers, The State University of New JerseyKeiji Seno - Kobe UniversityFumio Hayashi - Kobe UniversityRameshwar K. Sharma - Rutgers, The State University of New JerseyAlexander M. Dizhoor - Wayne State UniversityAkio Yamazaki - Wayne State University
- Publication Details
- The Journal of biological chemistry, v 274(22), pp 15547-15555
- Publisher
- Elsevier Inc
- Number of pages
- 9
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Neurobiology and Anatomy; Pennsylvania College of Optometry (PCO)
- Web of Science ID
- WOS:000080560100038
- Scopus ID
- 2-s2.0-0033024027
- Other Identifier
- 991022035261804721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Biochemistry & Molecular Biology