Bovine calbindin

Calbindin Dq M — 8.7 kDa) is another intracellular Ca -binding protein with unknown function. It was briefly mentioned in connection with Ca uptake and transport in the intestine and placenta (Section IV.A). Like the avian calbindin D2Sk, the Dgk calbindin has been observed in many types of tissue. The homology between the Dgk and D2Sk calbindins is much less than the name suggests both their syntheses are, however, regulated by vitamin D. The x-ray stmcture of bovine calbindin Dgk has been determined and refined to a resolution of 2.3 A, and a three-dimensional solution structure of porcine calbindin... 

A surprising discovery about the structure of bovine calbindin D9k in solution has also been made recently. Detailed analysis of the 2D H NMR spectrum of wild-type calbindin has revealed that it exists as a 3 1 equilibrium mixture of two forms, corresponding to a trans and cis conformation around the Gly-42-Pro-43 peptide bond. The global fold appears essentially the same in the two forms, and structural differences are primarily located in the inter-domain loop in which Pro-43 is located. 

The backbone trace of the solution structure of porcine calbindin D9t calculated from NMR data shown in two different views. The position of the calcium ions (blue spheres) is modeled after the crystal structure of bovine calbindin Dg. Figure kindly provided by M. Pique, M. Akke, and W. J. Chazin. 

Figure 2. Purification of Calchim-binding Proteins. A bovine retina extract (lane a) b applied to a phenyl-Sepharose column, and after washing the column (lane b), four prominent proteins are eluted the addition of EDTA (lane c). Recoverin is purified from the phenyl-Sepharose ehiate 1 Mono Q chromatogrt hy (lane d). The eluate fiom the phenyl-Sepharose column also can be i lied to an organomercurial column flowthrough (lane e), 10 fiM DTT wash (lane f), and C l is eluted with 10 mM DTT (lane g). Calbindin D-28K does not bind to phenyl-Sepharose but is eluted from a DEAE-Sephatose column by the addition of caldum (lane h). (Reproduced permission from ref. 10).

Fig. 19 Experimental example of ultra-high resolution multidimensional NMR spectra obtained by the proposed technique 174 intra-residual resonance from 89 h 4D HNCACO- H -coupled experiment acquired for 5-79 fragment of bovine Ca -loaded Calbindin protein. Depicted cross-sections of 4D cube 50 x 450 x 40 x 100 Hz surrounding the peak allow determination of coupling constants from resolved 4D E.COSY pattern. JcaHa = 135.9 Hz, Jhnhci = 5.8 Hz, = —5.0 Hz, Jnhhcx = —10 Hz with numerical resolution of 0.4 Hz/point, 1.7 Hz/point, 0.2 Hz/point, and 0.7 Hz/point in dimensions F], F2, F3, and F4, respectively. Reprinted with permission from [80]...

Gagnon, A., Simboli-CampbeU, M., Welsh, J. 1994. Induction of calbindin D-28k in Madin-Darby bovine kidney cells by l,25(OH)2D3. Kidney Int. 45 95-102. 

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