The requirement for ribonucleotides and ribonucleotide hydrolysis was examined at several distinct points during translocation of a secretory protein across the endoplasmic reticulum. We monitored binding of in vitro-assembled polysomes to microsomal membranes after removal of ATP and GTP. Ribonucleotides were not required for the initial low salt-insensitive attachment of the ribosome to the m...

Using antibodies isolated from glomeruli of nephritic rats we have previously identified a 330-kDa cell surface glycoprotein (gp330) as a major pathogenic antigen of Heymann nephritis (HN), an experimental model of human membranous glomerulonephritis. Recently, we have isolated a cDNA clone, C14, encoding a polypeptide that contains a pathogenic epitope of HN responsible for the initiation of t...

The AP-1 proteins are formed by the heterodimerization of Fos family members and Jun family members through a structural motif called the leucine zipper. The heterodimer can then bind DNA at a consensus site termed the AP-1 site and act as a transcription factor to modulate the expression of AP-1-responsive genes. All the Jun family members can also homodimerize to exert the same function. Gene...

The ribosome is a large complex catalyst responsible for the synthesis of new proteins, an essential function for life. New proteins emerge from the ribosome through an exit tunnel as nascent polypeptide chains. Recent findings indicate that tunnel interactions with the nascent polypeptide chain might be relevant for the regulation of translation. However, the specific ribosomal structural feat...

Allophycocyanin (AP) was isolated from extracts of the cyanobacterium Mastigocladus laminosus. A fraction enriched in AP-associated polypeptides with apparent molecular masses of 21-23 kDa in SDS-PAGE, was isolated on a preparative scale and identified as a homologous mixture of C-terminal fragments of the core-membrane linker polypeptide Lcm. The complex (alpha AP beta AP)3.21-23 kDa was recon...

Protein sequences evolved to fold in cells, including cotranslational folding of nascent polypeptide chains during their synthesis by the ribosome. The vectorial (N- to C-terminal) nature of cotranslational folding constrains the conformations of the nascent polypeptide chain in a manner not experienced by full-length chains diluted out of denaturant. We are still discovering to what extent the...