BSCL2

This gene encodes the multi-pass transmembrane protein protein seipin. This protein localizes to the endoplasmic reticulum and may be important for lipid droplet morphology. Mutations in this gene have been associated with congenital generalized lipodystrophy type 2 or Berardinelli-Seip syndrome, a rare autosomal recessive disease characterized by a near absence of adipose tissue and severe insulin resistance. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. Naturally occurring read-through transcription occurs between this locus and the neighboring locus HNRNPUL2 (heterogeneous nuclear ribonucleoprotein U-like 2).[provided by RefSeq, Mar 2011]

Full Name

BSCL2, Seipin Lipid Droplet Biogenesis Associated

Function

Plays a crucial role in the formation of lipid droplets (LDs) which are storage organelles at the center of lipid and energy homeostasis (PubMed:19278620, PubMed:21533227, PubMed:31708432, PubMed:30293840).
In association with TMEM159/LDAF1, defines the sites of LD formation in the ER (PubMed:31708432).
Also required for growth and maturation of small nascent LDs into larger mature LDs (PubMed:27564575).
Mediates the formation and/or stabilization of endoplasmic reticulum-lipid droplets (ER-LD) contacts, facilitating protein and lipid delivery from the ER into growing LDs (PubMed:31178403, PubMed:27879284).
Regulates the maturation of ZFYVE1-positive nascent LDs and the function of the RAB18-ZFYVE1 complex in mediating the formation of ER-LD contacts (PubMed:30970241).
Binds anionic phospholipids including phosphatidic acid (PubMed:30293840).
Plays an important role in the differentiation and development of adipocytes (By similarity).

Biological Process

Fat cell differentiation Source: UniProtKB
Lipid catabolic process Source: UniProtKB-KW
Lipid droplet formation Source: UniProtKB
Lipid droplet organization Source: UniProtKB
Lipid storage Source: UniProtKB
Negative regulation of lipid catabolic process Source: UniProtKB
Positive regulation of cold-induced thermogenesis Source: YuBioLab

Cellular Location

Endoplasmic reticulum membrane; Lipid droplet. Localizes at endoplasmic reticulum-lipid droplets (ER-LD) contact sites.

Involvement in disease

Congenital generalized lipodystrophy 2 (CGL2): An autosomal recessive disorder characterized by a near complete absence of adipose tissue, extreme insulin resistance, hypertriglyceridemia, hepatic steatosis and early onset of diabetes.
Spastic paraplegia 17, autosomal dominant (SPG17): A form of spastic paraplegia, a neurodegenerative disorder characterized by a slow, gradual, progressive weakness and spasticity of the lower limbs. Rate of progression and the severity of symptoms are quite variable. Initial symptoms may include difficulty with balance, weakness and stiffness in the legs, muscle spasms, and dragging the toes when walking. In some forms of the disorder, bladder symptoms (such as incontinence) may appear, or the weakness and stiffness may spread to other parts of the body. SPG17 is characterized by prominent amyotrophy of the hand muscles, the presence of mild to severe pyramidal tract signs and spastic paraplegia. SPG17 is a motor neuron disease overlapping with distal spinal muscular atrophy type 5.
Neuronopathy, distal hereditary motor, 5C (HMN5C): A form of distal hereditary motor neuronopathy, a heterogeneous group of neuromuscular diseases caused by selective degeneration of motor neurons in the anterior horn of the spinal cord, without sensory deficit in the posterior horn. HMN5C is characterized by distal muscular atrophy primarily affecting the upper limbs. Lower limb involvement may occur at the same time or later. Clinical features are highly variable even within families, and include poor fine hand motor skills, difficulty walking, foot deformities, spasticity and hyperreflexia. Some HMN5C patients show axonal peripheral neuropathy and distal sensory impairment. HMN5C inheritance is autosomal dominant with incomplete penetrance.
Encephalopathy, progressive, with or without lipodystrophy (PELD): A neurodegenerative disease characterized by developmental regression of motor and cognitive skills in the first years of life, often leading to death in the first decade, hyperactive behavior, seizures, tremor and ataxic gait. Patients may show a mild or typical lipodystrophic appearance.

Topology

Cytoplasmic: 1-26 aa
Helical: 27-47 aa
Lumenal: 48-242 aa
Helical: 243-263 aa
Cytoplasmic: 264-398 aa