Gluconeogenesis

When the mitochondria takes in pyruvate, does anyone here know how it determines whether to convert it to Oxaloacetate, then to Malate, then export the Malate across the membrane, or just go from Oxaloacetate to PEP directly?  I know that in the presence of lactate, NADH can be regenerated, so no malate is needed, but one the pyruvate enters the mitochondria, how does the mitochondria know that?

Thanks

Yeah i think so

It's been awhile since my biochem/mol. bio. days, but it has something to do with concentrations and phosphorylisation inhibiting one of the factors. Look for Biochemistry by voet, by far the best book that helped me in some tough scrapes. He goes through everything really well.