<prompt> Hydroxyproline and hydroxylysine occur principally inCollagenElastinSynoviumHyaline  <response>: Hydroxyproline and hydroxylysine occur principally in collagen. Since there is no tRNA for either hydroxylated amino acid, neither dietary hydroxyproline nor dietary hydroxylysine is incorporated during protein synthesis. Ref: Harper;s biochemistry; 30th edition; Chapter 27 Biosynthesis of the Nutritionally Nonessential Amino Acids 