Jeremy Corbyn has filled four vacancies in his shadow cabinet following the Brexit vote.
The Labour leader appointed Rebecca Long-Bailey as shadow business secretary, Sue Hayman as shadow environment secretary, Christina Rees as shadow Wales secretary and Peter Dowd as shadow chief secretary to the Treasury
In total, 52 Labour MPs rebelled against Mr Corbyn's orders and voted against triggering Article 50 on Wednesday night.
John McDonnell said it had been a "tough week" in response to fresh rebellion from Labour MPs over the Brexit Bill.
"In some ways, the divisions within the country are reflected in the Labour party," McDonnell said.
However he said that he could understand Labour MPs voted their constituencies.
The shadow chancellor admitted Clive Lewis quitting the shadow cabinet was "a real loss" to the party.
"He's really talented, Clive, but I'm sure he'll be back, he's got a major contribution to make in the future," he said.
McDonnell insisted that Labour would unite to protect the community from a 'Tory Brexit' and that Conservatives were "papering over the cracks" divisions within their own party.
Labour leader Jeremy Corbyn insisted that he has support from MPs on all other campaign issues and upcoming votes.
A total of 52 Labour MP's rebelled against their party leader's three-line whip for a second time to vote against Government's Brexit Bill.
Labour has called on the Government to set out its plans for immigration in post-Brexit UK.