A good professional printer should not ask for Adobe RGB or worse sRGB. They should supply an ICC profile specific to the printer paper they are sending data to. They should also have you embedd this profile into the data you send to them. Many systems are capable capturing and printing images that contain colours outside the gamut of even Adobe RGB. So edit in Prophot (no choice in LR) and softproof using the correct paper profile and either send directly to your printer or save image data with embedded profile for your lab.