Tertiary structure is the two-dimensional structure of a protein

Primary structure is the linear amino acid sequence of a protein

Secondary structure is determined by hydrogen bonding of the amino acid backbone

Quaternary structure is the three-dimensional structure of a multi-subunit protein

Quaternary structure

Tertiary structure

Secondary structure

Primary structure

More than one of these

Primary structure

Secondary structure

Quaternary structure

Tertiary structure

Transcription factors

Proteases

Lipases

Transmembrane proteins