The present disclosure relates to novel peptides and their uses including, proline-rich peptides that are useful for displaying a protein of interest at the surfaces of a host cell such as a yeast. Polynucleotides, proteins, vectors and host cells that comprise or encode the novel proline-rich peptides, including libraries comprising such polynucleotides, proteins, vectors and/or host cells that comprise or encode novel proline-rich peptides are provided. Methods and materials for display and expression of proteins of interest are provided. Methods and materials are also provided by the present disclosure for isolating peptides capable of displaying a protein of interest (e.g., a marker protein), for generating libraries to display and/or express proteins of interest (e.g., antibodies such as humanized antibodies), for generating secretion vectors for such proteins of interest, and for generating proteins of interest (e.g., antibodies).