Involved in the degradation of L-serine via 3-hydroxypyruvate. Catalyzes the transamination between L-serine and pyruvate to yield 3-hydroxypyruvate and alanine. L-serine + pyruvate = 3-hydroxypyruvate + L-alanine Belongs to the class-V pyridoxal-phosphate-dependent aminotransferase family.