| The translocon in the endoplasmic reticulum (ER) membrane is composed of several proteins that associate to form an aqueous pore through which secretory proteins and luminal domains of membrane proteins pass from the cytoplasm to the ER lumen. Here we have attempted to make an extensive inventory of translocon components in different species using a bioinformatics approach with PSI-BLAST as one important tool. The major purpose of this study was 1) to identify homologs of translocon component not previous recognized, 2) to search for novel protein family relationships and 3) to obtain a better understanding of the evolution of the translocon machinery. |