David Cameron has kicked off a coalition reshuffle, with Scottish Secretary Michael Moore among the casualties.
The Liberal Democrat's Cabinet post is being taken by the party's chief whip Alistair Carmichael - just a year before the crucial referendum on independence north of the border.
Tory Esther McVey has been pushed up the ranks at the Department for Work and Pensions to become employment minister, while Greg Hands - a close ally of Chancellor George Osborne - has been made deputy chief whip for the Conservatives.
Greg Clark has been moved from the Treasury to take on responsibilities for cities and constitutional reform at the Cabinet Office, and former Northern Ireland minister Mike Penning becomes a minister at Work and Pensions.
The shake-up is expected to see women and northern MPs promoted to more senior posts as the Prime Minister gears up for the 2015 election. No further changes are due to the Cabinet.
Meanwhile, Labour leader Ed Miliband is also preparing to make changes to his top team.
Sajid Javid moves up a rung to replace Greg Clark as Financial Secretary to the Treasury, while Mr Clark moves to the Cabinet Office to become Cities and Constitution Minister.
Mike Penning is leaving the Northern Ireland brief to become a minister at the Department for Work and Pensions.
Nicky Morgan has been promoted from assistant whip to Economic Secretary to the Treasury, No 10 confirmed.
Mr Moore said he was disappointed, but that he would continue to play a role inensuring Scotland remains a part of the United Kingdom.
He told the BBC: “I’m disappointed to be leaving office right now. But I’m very pleased at what I have been able to achieve in the last couple of years, particularly in the constitutional debate on the Scotland Act and the Edinburgh Agreement.”
The Scotland Act 2012 had the aim of devolving further powers to Scotland, while the Edinburgh Agreement (2012) enshrined in law a vote allowing the Scottish public to say whether or not they wish to remain to leave the UK.
Mr Moore added: “But this big decision that we’re taking as a country is bigger than one individual, bigger than one party. I look forward to continuing to play a really big role in the constitutional debate over the course of the next 12 months.”