Cannot resolve PlusClient

I try to integrate my android-application to g+. I try to add PlusClient to initialize it. But AndroidStudio says : Cannot resolve PlusClient. I added these import-header:

import com.google.android.gms.plus.Plus;

Also, I tryed to add these import-header:

import com.google.android.gms.plus.PlusClient;

but AndroidStudio cannot find PlusClient after .plus. I'm using 22 api. How to fix it? Does Api still support PlusClient? And is any differences bettween Plus and PlusClient?