Storella JR, DM Wojchowski and JG Kunkel. 1985. Structure and embryonic degradation of two native vitellins in the cockroach, Periplaneta americana. Insect Biochem. 15: 259-275.
Multiple vitellogenins (VG) are found in species from all major families of cockroaches. Proof that observed multiple VGs are actually distinct proteins and not artifacts of differential processing requires careful examination. In Periplaneta americana two immunologically and electrophoretically distinct vitellins (VTs) of similar native size exist in the egg. VT1 is composed of four major peptides of molecular weights 170, 105, 92 and 78 K. VT2 is composed of three major peptides of molecular weights 105, 101 and 60 K. A peptide with molecular weight of about 105 K is found in both VG1 and VG2 and a similar sized peptide is also conserved in the VGs of all other Blatinae subfamily members examined despite the distant immunological relation of these proteins. The 170 K peptide of VT1 is likely to be a processing intermediate of the 92 K and the 78 K peptides. Each VT from a freshly ovulated egg is immunologically identical to and has essentially the same peptide substructure as its serum precursor. The cumulative Mr of the constituent peptides of each VG is approx. 260 K, consistent with 17S native dimeric molecules of approx. 520 K Mr. A specific and limited cleavage of VT major peptides occurs during early embryogenesis (at 30°C, 9 days after ovulation) resulting in a partial loss of immunological determinants. During subsequent yolk utilization the VTs undergo gradual degradation.