U. Wojda et J. Kuznicki, CALCYCLIN FROM MOUSE EHRLICH ASCITES TUMOR-CELLS AND RABBIT LUNG FORMNONCOVALENT DIMERS, Biochimica et biophysica acta. Protein structure and molecular enzymology, 1209(2), 1994, pp. 248-252
Crosslinking treatments of fresh cytosol from mouse Ehrlich ascites tu
mor (EAT) cells revealed the existence of calcyclin dimers which were
sensitive to SDS, but not to reducing agents, which suggests the exist
ence of non-covalent dimers. In stored EAT cell cytosol and preparatio
ns of purified calcyclin dimers were also formed by S-S bridging (cova
lent dimers). The S-S dimers did not bind to organomercurial Agarose a
nd could be separated from reduced forms of calcyclin that bound to th
e resin. Calcyclin eluted from the resin with DTT was a mixture of mon
omers and non-covalent dimers as shown by crosslinking and subsequent
immunoblotting. Calcyclin from rabbit lung, lacking a cysteine residue
, could also be crosslinked as a dimer. It is suggested that the abili
ty of calcyclin to form non-covalent dimers is of physiological signif
icance.