Structure of human voltage-dependent calcium channel (VDCC) beta 3 subunit gene

In excitable and endocrine organs, calcium influxes through the voltage-dependent calcium channel (VDCC), composed of four (alpha 1, alpha 2, beta, and gamma) subunits. Four isoforms of beta subunits (beta 1, beta 2, beta 3, beta 4) are known to exist, The cytoplasmic beta subunits regulate the channel activity by accelerating the kinetics of activation and inactivation through phosphorylation. Regulation of calcium channel activities are also provided by alternative splicing of the beta subunits. To elucidate the genomic organization of the VDCC beta 3 subunit gene, two genomic clones were isolated from human genomic liabrary using the whole rat cDNA for beta 3 subunit as a probe. The beta 3 subunit gene in lamda phage DNA was analyzed by Southern hybridization and sequencing. A 19.1 kb clone (2BHG13) contained the whole beta 3 cDNA sequence, consisting at least 14 exons. The deduced amino acid sequence from the exons shows 97% similarity with that of rat gene. Two alternatively spliced forms of beta 3 subunit at 5'-end were found. The beta 3 subunit had many possible phosphorylation sites. Alternative splicing of beta 3 subunit mRNA at 5'-end and phosphorylation of the beta 3 subunit protein may play a regulatory role in calcium influxes.

A clinical study on febrile convulsion

Although febrile convulsion (FC) is a common clinical entity with a high recurrence rate, no specific factors have been identified to be highly predictive of its recurrence. A total of 114 cases of FC identified during a 28 month period (January, 1989-May, 1991) was analysed. A slight predominance of boys over girls (1.3 to 1.0) was observed. the majority of cases (89.4%) were under 3 years of age and the most common age range for the onset of FC was 1~2 years. The most common form of FC was tonic type (54.0%), followed by tonic-clonic (32.5%), clonic (5.3%), and complex partial type (5.3%). Most FC episodes lasted less than 5 minutes (81.6%), and common clinical diagnosis underlying FC were as follows: pharyngotonsillitis (64.0%), bronchitis and/or pneumonia(16.7%), and gastroenteritis (9.7%). The family history for seizure disorder was present in 27.2% of the cases: FC in 21.1%, epiepsy in 4.4%, and both in 1.8%. Among 78 cases of the first FC, 43 cases were followed for 5 to 29 months without prophylactic anticonvulsant therapy. The overall recurrence rate of FC in this group was 67.4% and the highest incidence was observed in patients less than one year old (86.7%). A higher recurrence rate (80%) was observed in patients whose body temperature was lower than 39degrees C, as opposed to higher than 39degrees C (50%). It is concluded that the recurrence of FC is positively correlated with factors such as younger age (less than one year old), and lower body temperature at the time of onset of FC.