A Joint Saga: Human Leukocyte Antigen (HLA) B27 Ankylosing Spondylitis and Sacroiliitis Association with Henoch-Schönlein Purpura.

Henoch-Schönlein purpura (HSP) or IgA vasculitis is a small-vessel vasculitis mediated by IgA deposition, often associated with upper respiratory tract infection and family history. However, there is a rare correlation to human leukocyte antigen (HLA) B27 arthropathy. We present a case of a young boy diagnosed with HSP suffering from arthritis, gait disturbance, and weakness throughout childhood, ultimately diagnosed with ankylosing spondylitis and sacroiliitis clinically, with confirmation through X-ray and supporting HLA B27 testing.

Ex-aspirated: A Case of Dental Product Aspiration With Retrieval Methodology and Current Review.

Foreign body aspiration is of significant prevalence in the pediatric and young adult populations. After dental work, patients are more likely to develop pulmonary symptoms secondary to aspiration events within the tracheobronchial tree. Herein, we describe the clinical case of a 22-year-old man with a past medical history of epilepsy and tuberous sclerosis who presented to his primary care provider for chronic coughing and wheezing.

Ubiquitin receptors are required for substrate-mediated activation of the proteasome's unfolding ability.

The ubiquitin-proteasome system (UPS) is responsible for the bulk of protein degradation in eukaryotic cells, but the factors that cause different substrates to be unfolded and degraded to different extents are still poorly understood. We previously showed that polyubiquitinated substrates were degraded with greater processivity (with a higher tendency to be unfolded and degraded than released) than ubiquitin-independent substrates. Thus, even though ubiquitin chains are removed before unfolding and degradation occur, they affect the unfolding of a protein domain.

Substrate Ubiquitination Controls the Unfolding Ability of the Proteasome.

In eukaryotic cells, proteins are targeted to the proteasome for degradation by polyubiquitination. These proteins bind to ubiquitin receptors, are engaged and unfolded by proteasomal ATPases, and are processively degraded. The factors determining to what extent the proteasome can successfully unfold and degrade a substrate are still poorly understood.

Slipping up: partial substrate degradation by ATP-dependent proteases.

ATP-dependent proteases are present in all organisms, where they are responsible for much of intracellular protein degradation. Most proteins are processively unfolded and degraded into small peptides; however, in a few so-called slippery substrates, the protease stalls at a folded domain and releases a large protein fragment. In this review, we describe the properties of physiological slippery substrates that are processed in this manner by ATP-dependent proteases and the recent advances that have been made in understanding the mechanism underlying their partial degradation.