researchers investigating the regulation of neurotransmitter release from presynaptic neurons proposed a model (figure 1) in which cdk5, a protein expressed in axon terminals, inhibits the movement of synaptic vesicles to the presynaptic membrane. to test their model, the researchers used a modified version of green fluorescent protein (gfp*). in slightly alkaline conditions, gfp* exhibits a bright green fluorescence. in acidic conditions, gfp* exhibits no fluorescence. using standard techniques, the gene encoding gfp* is easily introduced into living cells. by engineering the expression of gfp* in laboratory-cultured nerve cells, the researchers found that a bright green fluorescence was exhibited only when a presynaptic neuron was given a certain stimulus. question previous experiments indicate that cdk5 is active only when attached to a protein called p35. which of the following best predicts how p35 might play a role in regulating neuron function? responses