The fatty acid elongase-1 β-ketoacyl-CoA synthase, FAE1 KCS, a seed-specific elongase condensing enzyme from Arabidopsis, is involved in the production of eicosenoic (C20:1) and erucic (C22:1) acids. Alignment of the amino acid sequences of FAE1 KCS, KCS1

Mesangial cells can be induced to express group IIA and group V secretory phospholipase A2 (sPLA2) at the mRNA level and at the protein level. In this report we quantitatively analyze the expression of both proteins in stimulated cells by Western blot techniques. We found that 75–80% of the total amount of synthesized group IIA sPLA2 was secreted. The synthesized group V sPLA2, however, was present almost exclusively intracellularly. The amount of group V present in the cell was comparable to the intracellular amount of group IIA sPLA2. We furthermore studied the localization and routing of both proteins. Using fusion proteins of the group IIA or group V pre-sPLA2 with green fluorescent protein it was established that both presequences are able to direct the proteins to the Golgi system. In immunofluorescence studies group V sPLA2 expressed by rat mesangial cells was located in a punctate pattern in the cytosol with an enrichment near the nucleus. Immunofluorescent confocal laser scanning microscopy revealed that the group V and IIA sPLA2 show partial colocalization in a Golgi-like structure in the inner part in the cell, but no colocalization was seen in the vesicles in the cytoplasm. The images also showed that group IIA sPLA2 was located throughout the cell while group V was mainly present in the inner part of the cell. After treatment of the cells with brefeldin A or monensin the group IIA enzyme could no longer be detected, while group V sPLA2 was still present although its localization was somewhat dependent on the treatment. Collectively, these results indicate that the two enzymes differ in both localization and routing in the cell, which underscores the hypothesis that the enzymes might have different functions.