A Calcium-Dependent Protein Kinase with a Regulatory Domain Similar to Calmodulin

Abstract

Calcium can function as a second messenger through stimulation of calcium-dependent protein kinases. A protein kinase that requires calcium but not calmodulin or phospholipids for activity has been purified from soybean. The kinase itself binds calcium with high affinity. A complementary DNA clone for this kinase has been identified; it encodes a protein with a predicted molecular mass of 57,175 daltons. This protein contains a catalytic domain similar to that of calmodulin-dependent kinases and a calmodulin-like region with four calcium binding domains (EF hands). The predicted structure of this kinase explains its direct regulation via calcium binding and establishes it as a prototype for a new family of calcium-regulated protein kinases.

Cellular localization and biochemical characterization of a novel calcium-dependent protein kinase from tobacco

“…3E), suggesting that the junction domain may be a negative regulatory domain of the kinase. This result is supporting the model of CPKs activation that the binding of Ca 2+ can trigger conformational change of the kinase to release an auto-inhibitor from the active site [25]. In the absence of the calcium-binding Yun WANG et al domain, access to the active site is permanently blocked by the pseudosubstrate auto-inhibitor rendering the enzyme inactive [6].…”

Characterisation and cloning of a calmodulin-like domain protein kinase from Chlamydomonas moewusii (Gerloff )

“…Since the direct stimulation of protein kinase activity by calcium is typical of CDPKs (Harper et al 1991;Roberts and Harmon 1992), a mAb directed against the soybean CDPKa (Putnam-Evans et al 1989) was used to immunologically detect related proteins in extracts of Chlamydomonas¯agella. A protein with an apparent MW of 65-kDa (Fig.…”

“…Alignment of the CCK1 junction domain with that of other CDPKs and the relative homologies of the kinase-and calmodulin-like domains. A Three or more identical amino acids in the junction domains of CCK1, CDPKa (Harper et al 1991), AK1 (Harper et al 1993), AtCDPK1 (Urao et al 1994), SPK1 (Kawasaki et al 1993), ZmCDPK (Estruch et al 1994) and DcCDPK (Suen and Choi 1991) are shown. B Phylogenetic relations of the kinase domains of the CDPKs from Chlamydomonas (CCK1), soybean (CDPKa), Arabidopsis (AK1) and carrot (DcCDPK) are shown compared with human PKA, PKCa (Finkenzeller et al 1990), rat MLCK (Roush et al 1988) and mouse calcium/calmodulin-dependent kinase II (Karls et al 1992).…”

A novelToxoplasma gondiicalcium-dependent protein kinase

“…Not surprisingly, sequence comparisons showed that TgCDPK4 was most similar to CDPKs of apicomplexan parasites P. falciparum PfCDPK2 (Farper et al, 1997) and E. maxima EmCDPK (Dunn et al, 1996) and plants such as A. thaliana CDPK/AK1 (Harper et al, 1993) and soybean CDPKg. (Harper et al, 1991. The sequence of TgCDPK4 has been deposited in Genbank under the accession number AJ488146.…”

“…An unusual class of calcium-dependent protein kinases has been described containing calmodulin-like domains (CDPKs) and the kinases can be activated by calcium in the absence of calmodulin, or phospholipids. First described in plants (Harper et al, 1991) such enzymes have also been identified in algae (Yuasa & Muto, 1992) and in apicomplexan parasites such as Eimeria maxima (Dunn et al, 1996) and P. falciparum (Li et al, 2000; …”