According to a statement released, Moloto had joined the ANC parliamentary caucus in 2005 and served under seven chief whips "with dedication, diligence and uncompromising loyalty".
"Comrade Moloto has been an invaluable part of the ANC Caucus and the ANC at large. We wish him the very best in future endeavours he wishes to explore. He can rely on our support wherever the future leads him," Mthembu said.
The statement did not mention where Mothapo was headed, but said it had started a process to find his replacement.
"The Office of the Chief Whip is making the necessary arrangements in view of Cde Moloto’s departure and an announcement in this regard will be made at an appropriate time."