Right handed type I:A motif of four consecutive residues that may contain one H-bond, which, if present, is between the main-chain CO of the first residue and the main-chain NH of the fourth. It is characterized by the dihedral angles: Residue(i+1): -140 degrees < phi < -20 degrees, -90 degrees < psi < +40 degrees. Residue(i+2): -140 degrees < phi < -20 degrees, -90 degrees < psi < +40 degrees.