48 boards, IMPs
1NT = 15-17 (this is in our style for a 1NT opening - we don't like 5-card majors, but we like long minors)
2♠ = clubs (any strength)
2NT = denies the A or K to 3 or more clubs
3♠ = natural, might only be 4-5
3NT = no slam interest
4♣ = 4-6 (or 4-7) slam interest even opposite no fit (with 4(30)6 partner might choose to pattern out, it would depend on the honour structure)
Now what?
4D, 4H, 4S would be cue bids (first round control in a red suit, A or K in partner's suit spades)
4NT would be discouraging
5C would systemically be 'encouraging' but may just suggest this is the better game as it should deny a cue bid.

Help

Uncontested auction
1NT 2♠
2NT 3♠
3NT 4♣