yes it is threaded " features a 1/2"-28 thread pattern for popular muzzle accessories (thread protector included)." https://ruger.com/products/markIV2245Lite/specSheets/43915.html

Yes the barrel is threaded
Ruger RUG MKIV 2245 LT 22PST 4.4 PRP * Model: Mark IV * Caliber: 22LR * Action: Single Action * Capacity: 10+1 * Finish: Purple Anodized * Stock: Black Synthetic/ Checkered 1911-Style Grips * Sights: Front: Fixed Rear: Adjustable * Barrel: 4.40 1/2-28 Threaded Barrel * Length: 8.40

Larry, yes Sir. It is has a 1/2-28 Threaded Barrel.