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Calmodulin of the baker's yeast (Saccharomyces cerevisiae) showed a similar affinity for Ca2+ to that of vertebrate calmodulin. The maximum binding number of Ca2+ to yeast calmodulin was, however, 3 mol/mol, which is lower than that of vertebrate calmodulin (4 mol/mol). The same maximum activity of porcine brain phosphodiesterase was attained when 100 times higher concentration of yeast calmodulin than that of vertebrate calmodulin was added. On the other hand, the maximum activation of chicken gizzard myosin light chain kinase was attained with 1,000 times higher concentration of yeast calmodulin than that of vertebrate calmodulin, and the maximum activity with yeast calmodulin was less than 1/5 of that with vertebrate calmodulin. Several amino acid substitutions observed in the yeast calmodulin, particularly at the alpha-helical rod connecting the two globular domains, may affect the interaction mode of various target enzymes with this calmodulin.

Equations for permeation through laminated composites (slabs) made by two components have been derived under the same conditions as in previous papers4, 5) in which the diffusion coefficient Di is constant and the equilibrium sorption Csi follows Henry's law in each component layer i.Both the concentration distribution in the various laminated composites and permeation rate through them are calculated, by substituting Di and Csi of p-nitroaniline in each component film (nylon 6, cellulose diacetate, cellulose triacetate) into the equations. Good agreement is obtained between the calculations and experiments for the permeation in such systems.Variations of over all diffusion coefficients (DPov, DLov) obtained by the permeation rate and time lag, respectively, are demonstrated against the volume fraction of a component in the composites. It is revealed that the DPov depends on only the volume fraction, whereas the DLov, depends on also the order of components in the composites.

Neuronal Cdc2-like kinase, Nclk, is a heterodimer of cyclin-dependent protein kinase 5 (Cdk5) and a 25-kDa essential regulatory subunit that is derived from a 35-kDa brain- and neuron-specific protein. This protein is called neuronal Cdk5 activator, p25/35nck5a. Nclk is one of the best characterized Cdc2 family kinases whose primary function is not cell cycle related. It has been suggested that this protein kinase plays important roles in neurocytoskeleton dynamics and its loss of regulation has been implicated in Alzheimer pathology. As a member of the Cdc2-like kinase family, Nclk shares many common properties with other members of the Cdc2-like kinase family. It also possesses unique characteristics that may be related to its distinct and noncell cycle related functions. The regulatory and functional properties of Nclk are reviewed in this communication.Key words: Cdc2 kinase, Cdk5, neuronal Cdk5 activator.