Protasov, 47, of Sunnyvale, was found around 7:45 p.m. Thursday in his Infiniti G35 on the shoulder of the highway near the Mathilda Avenue exit, California Highway Patrol Officer Kevin Bartlett said.
He was alone inside the car, Bartlett said.
Emergency crews attempted to revive Protasov but were unsuccessful, and he was pronounced dead at the scene.
His car did not appear to have been involved in a collision, Bartlett said.
Protasov's cause of death has yet to be determined, but it does not appear to be suspicious, Bartlett said.