SPTBN1

Spectrin beta chain, brain 1 is a protein that in humans is encoded by the SPTBN1 gene.

Function

Spectrin is an actin crosslinking and molecular scaffold protein that links the plasma membrane to the actin cytoskeleton, and functions in the determination of cell shape, arrangement of transmembrane proteins, and organization of organelles. It is composed of two antiparallel dimers of alpha- and beta- subunits. This gene is one member of a family of beta-spectrin genes. The encoded protein contains an N-terminal actin-binding domain, and 17 spectrin repeats that are involved in dimer formation. Multiple transcript variants encoding different isoforms have been found for this gene.

Interactions

SPTBN1 has been shown to interact with Merlin.

Model organisms

Spnb2 knockout mouse phenotype

Characteristic	Phenotype
Homozygote viability	Abnormal
Recessive lethal study	Abnormal
Body weight	Normal
Anxiety	Normal
Neurological assessment	Normal
Grip strength	Normal
Hot plate	Normal
Dysmorphology	Normal
Indirect calorimetry	Normal
Glucose tolerance test	Normal
Auditory brainstem response	Normal
DEXA	Normal
Radiography	Normal
Body temperature	Normal
Eye morphology	Normal
Clinical chemistry	Abnormal
Plasma immunoglobulins	Normal
Haematology	Normal
Peripheral blood lymphocytes	Normal
Micronucleus test	Normal
Heart weight	Normal
Tail epidermis wholemount	Normal
Skin Histopathology	Normal
Brain histopathology	Normal
MicroCT & Quantitative Faxitron	Abnormal
Salmonella infection	Normal
Citrobacter infection	Normal
All tests and analysis from

Model organisms have been used in the study of spectrin function. A conditional knockout mouse line, called Spnb2^{tm1a(EUCOMM)Wtsi} was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists.

Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion. Twenty seven tests were carried out on mutant mice and four significant abnormalities were observed. Few homozygous mutant embryos were identified during gestation and those that were present displayed oedema. None survived until weaning. The remaining tests were carried out on heterozygous mutant adult mice. These animals had a decreased length of long bones, while males also displayed hypoalbuminemia .