In extension of earlier reports, none of the 80 Asn-Pro-Ser/Thr found were glycosylated, and a markedly low level of glycosylation was seen in sequons with Pro at the position following the Ser/Thr. In addition, a general observation was made that the considerable number of glycosylated sequons in the C-terminal 10 residues of glycoproteins suggests that N-glycosylation in these cases may be posttranslational and not cotranslational, as widely accepted.