Subcellular distribution of pyridoxal kinase in ox retina.

PL kinase activity has been determined in primary and secondary subcellular fractions of ox retina. Enzymic activity is predominantly located in the soluble fraction (S3). About 65% of the recovered PL kinase activity of crude mitochondria is released from synaptosomal fraction after hypoosmotic treatment. PL kinase activity in supernatant fraction (S3) does not exceed the enzyme activity measured in the homogenate, excluding the presence of a particulate-bound inhibitor to PL kinase in the homogenate. The possible physiological significance of PL kinase cellular compartmentation has been considered.